|
Fair Value Measurements (Details) (USD $)
In Thousands, unless otherwise specified
|
12 Months Ended |
|
|
Dec. 31, 2014
|
Dec. 31, 2013
|
| Minimum |
|
|
| Fair Value Measurements |
|
|
| Maturity period of long-term investments |
1 year |
|
| Maximum |
|
|
| Fair Value Measurements |
|
|
| Maturity period of long-term investments |
2 years |
|
| Measured on a recurring basis |
|
|
| Fair Value Measurements |
|
|
| Assets, Adjusted Cost |
97,266 |
$ 84,546 |
| Assets, Unrealized Gains |
2 |
|
| Assets, Unrealized Losses |
(49) |
|
| Assets, Fair Value |
97,219 |
84,546 |
| Measured on a recurring basis | Cash and Cash Equivalents |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
29,187 |
84,546 |
| Measured on a recurring basis | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
53,523 |
|
| Measured on a recurring basis | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
14,509 |
|
| Measured on a recurring basis | Cash |
|
|
| Fair Value Measurements |
|
|
| Assets, Adjusted Cost |
13,077 |
5,533 |
| Assets, Fair Value |
13,077 |
5,533 |
| Measured on a recurring basis | Cash | Cash and Cash Equivalents |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
13,077 |
5,533 |
| Measured on a recurring basis | Level 1 |
|
|
| Fair Value Measurements |
|
|
| Assets, Adjusted Cost |
16,110 |
79,013 |
| Assets, Fair Value |
16,110 |
79,013 |
| Measured on a recurring basis | Level 1 | Cash and Cash Equivalents |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
16,110 |
79,013 |
| Measured on a recurring basis | Level 1 | Money market funds |
|
|
| Fair Value Measurements |
|
|
| Assets, Adjusted Cost |
16,110 |
79,013 |
| Assets, Fair Value |
16,110 |
79,013 |
| Measured on a recurring basis | Level 1 | Money market funds | Cash and Cash Equivalents |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
16,110 |
79,013 |
| Measured on a recurring basis | Level 2 |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
68,079 |
|
| Unrealized Gains, available-for-sale investments |
2 |
|
| Unrealized Losses, available-for-sale investments |
(49) |
|
| Fair value, Available-for-sale investments |
68,032 |
|
| Measured on a recurring basis | Level 2 | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
53,523 |
|
| Measured on a recurring basis | Level 2 | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
14,509 |
|
| Measured on a recurring basis | Level 2 | Asset-backed securities |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
4,458 |
|
| Unrealized Losses, available-for-sale investments |
(3) |
|
| Fair value, Available-for-sale investments |
4,455 |
|
| Measured on a recurring basis | Level 2 | Asset-backed securities | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
4,455 |
|
| Measured on a recurring basis | Level 2 | Corporate bonds |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
54,321 |
|
| Unrealized Gains, available-for-sale investments |
2 |
|
| Unrealized Losses, available-for-sale investments |
(46) |
|
| Fair value, Available-for-sale investments |
54,277 |
|
| Measured on a recurring basis | Level 2 | Corporate bonds | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
46,726 |
|
| Measured on a recurring basis | Level 2 | Corporate bonds | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
7,551 |
|
| Measured on a recurring basis | Level 2 | Commercial paper |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
6,797 |
|
| Fair value, Available-for-sale investments |
6,797 |
|
| Measured on a recurring basis | Level 2 | Commercial paper | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
6,797 |
|
| Measured on a recurring basis | Level 2 | U.S. agency securities |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
2,503 |
|
| Fair value, Available-for-sale investments |
2,503 |
|
| Measured on a recurring basis | Level 2 | U.S. agency securities | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
2,503 |
|