|
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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Dec. 31, 2012
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Dec. 31, 2011
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
$ 70,825
|
$ 20,258
|
|
Money market funds [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
5,886
|
4,050
|
|
Certificate of deposits [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
1,185
|
|
|
Corporate debt securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
20,242
|
4,690
|
|
Government securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
27,899
|
5,970
|
|
Commercial paper [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
15,613
|
5,548
|
|
Basis of Fair Value Measurements, Level 1 [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
5,886
|
4,050
|
|
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 |
5,886
|
4,050
|
|
Basis of Fair Value Measurements, Level 2 [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
64,939
|
16,208
|
|
Basis of Fair Value Measurements, Level 2 [Member] | Certificate of deposits [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
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 |
20,242
|
4,690
|
|
Basis of Fair Value Measurements, Level 2 [Member] | Government securities [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
27,899
|
5,970
|
|
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 |
15,613
|
5,548
|
|
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] | Certificate of deposits [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] | 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] | Commercial paper [Member]
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total cash equivalents and marketable securities |
|
|