|
Fair Value Measurements and Marketable Securities - Summary of Company's Available-for-Sale Securities (Detail) (USD $)
In Thousands, unless otherwise specified
|
Mar. 31, 2015
|
Dec. 31, 2014
|
| Schedule Of Available For Sale Securities [Line Items] |
|
|
| Cost Basis |
$ 62,038 |
$ 50,222 |
| Unrealized Gain |
6 |
4 |
| Unrealized Loss |
(21) |
(17) |
| Fair Value |
62,023 |
50,209 |
| Money Market Funds |
|
|
| Schedule Of Available For Sale Securities [Line Items] |
|
|
| Cost Basis |
10,366 |
3,369 |
| Unrealized Gain |
0 |
0 |
| Unrealized Loss |
0 |
0 |
| Fair Value |
10,366 |
3,369 |
| Certificates of Deposit |
|
|
| Schedule Of Available For Sale Securities [Line Items] |
|
|
| Cost Basis |
1,475 |
2,505 |
| Unrealized Gain |
0 |
0 |
| Unrealized Loss |
0 |
0 |
| Fair Value |
1,475 |
2,505 |
| Corporate Debt Securities |
|
|
| Schedule Of Available For Sale Securities [Line Items] |
|
|
| Cost Basis |
31,950 |
28,094 |
| Unrealized Gain |
4 |
1 |
| Unrealized Loss |
(19) |
(14) |
| Fair Value |
31,935 |
28,081 |
| U.S. Government Securities |
|
|
| Schedule Of Available For Sale Securities [Line Items] |
|
|
| Cost Basis |
24,021 |
19,123 |
| Unrealized Gain |
2 |
3 |
| Unrealized Loss |
(2) |
(3) |
| Fair Value |
24,021 |
19,123 |
| Commercial Paper |
|
|
| Schedule Of Available For Sale Securities [Line Items] |
|
|
| Cost Basis |
14,240 |
5,499 |
| Unrealized Gain |
0 |
0 |
| Unrealized Loss |
0 |
0 |
| Fair Value |
14,240 |
5,499 |
| Marketable Securities Including Cash Equivalents |
|
|
| Schedule Of Available For Sale Securities [Line Items] |
|
|
| Cost Basis |
82,052 |
58,590 |
| Unrealized Gain |
6 |
4 |
| Unrealized Loss |
(21) |
(17) |
| Fair Value |
82,037 |
58,577 |
| Less Cash Equivalents |
|
|
| Schedule Of Available For Sale Securities [Line Items] |
|
|
| Cost Basis |
20,014 |
8,368 |
| Unrealized Gain |
0 |
0 |
| Unrealized Loss |
0 |
0 |
| Fair Value |
$ 20,014 |
$ 8,368 |