Fair Value Measurements and Marketable Securities - Financial Assets at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified
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Mar. 31, 2014
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Dec. 31, 2013
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
$ 86,386
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$ 82,033
|
Money Market Funds [Member]
|
|
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
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Total cash equivalents and marketable securities |
5,001
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4,285
|
Certificates of Deposit [Member]
|
|
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
1,464
|
1,584
|
Corporate Debt Securities [Member]
|
|
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
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Total cash equivalents and marketable securities |
55,317
|
49,019
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U. S. Government Securities [Member]
|
|
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
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Total cash equivalents and marketable securities |
18,990
|
21,731
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Municipal Securities [Member]
|
|
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
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Total cash equivalents and marketable securities |
1,618
|
2,815
|
Commercial Paper [Member]
|
|
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
3,996
|
2,599
|
Basis of Fair Value Measurements, Level 1 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
5,001
|
4,285
|
Basis of Fair Value Measurements, Level 1 [Member] | Money Market Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
5,001
|
4,285
|
Basis of Fair Value Measurements, Level 1 [Member] | Certificates of Deposit [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 1 [Member] | Corporate Debt Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 1 [Member] | U. S. Government Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 1 [Member] | Municipal Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 1 [Member] | Commercial Paper [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 2 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
81,385
|
77,748
|
Basis of Fair Value Measurements, Level 2 [Member] | Money Market Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 2 [Member] | Certificates of Deposit [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
1,464
|
1,584
|
Basis of Fair Value Measurements, Level 2 [Member] | Corporate Debt Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
55,317
|
49,019
|
Basis of Fair Value Measurements, Level 2 [Member] | U. S. Government Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
18,990
|
21,731
|
Basis of Fair Value Measurements, Level 2 [Member] | Municipal Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
1,618
|
2,815
|
Basis of Fair Value Measurements, Level 2 [Member] | Commercial Paper [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
3,996
|
2,599
|
Basis of Fair Value Measurements, Level 3 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Money Market Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Certificates of Deposit [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Corporate Debt Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 3 [Member] | U. S. Government Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Municipal Securities [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Commercial Paper [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Total cash equivalents and marketable securities |
|
|