|
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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Sep. 30, 2013
|
Dec. 31, 2012
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
$ 91,914
|
$ 70,825
|
|
Money market funds [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
4,001
|
5,886
|
|
Certificates of deposit [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
1,880
|
1,185
|
|
Corporate debt securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
56,484
|
20,242
|
|
U.S. Government securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
26,089
|
27,899
|
|
Municipal securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
1,211
|
|
|
Commercial paper [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
2,249
|
15,613
|
|
Basis of Fair Value Measurements, Level 1 [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
4,001
|
5,886
|
|
Basis of Fair Value Measurements, Level 1 [Member] | Money market funds [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
4,001
|
5,886
|
|
Basis of Fair Value Measurements, Level 1 [Member] | Certificates of deposit [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 1 [Member] | Corporate debt securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 1 [Member] | U.S. Government securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 1 [Member] | Municipal securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 1 [Member] | Commercial paper [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 2 [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
87,913
|
64,939
|
|
Basis of Fair Value Measurements, Level 2 [Member] | Money market funds [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 2 [Member] | Certificates of deposit [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
1,880
|
1,185
|
|
Basis of Fair Value Measurements, Level 2 [Member] | Corporate debt securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
56,484
|
20,242
|
|
Basis of Fair Value Measurements, Level 2 [Member] | U.S. Government securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
26,089
|
27,899
|
|
Basis of Fair Value Measurements, Level 2 [Member] | Municipal securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
1,211
|
|
|
Basis of Fair Value Measurements, Level 2 [Member] | Commercial paper [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
2,249
|
15,613
|
|
Basis of Fair Value Measurements, Level 3 [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Money market funds [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Certificates of deposit [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Corporate debt securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 3 [Member] | U.S. Government securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Municipal securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|
|
Basis of Fair Value Measurements, Level 3 [Member] | Commercial paper [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
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