Fair Value Measurements (Details) - USD ($)
$ in Thousands |
12 Months Ended |
|
Dec. 31, 2015 |
Dec. 31, 2014 |
| Fair Value Measurements |
|
|
| Assets, Fair Value |
$ 0
|
|
| Liabilities, Fair Value |
0
|
|
| Foreign Exchange Contract | Other Income Expense | Not Designated as Hedging Instrument |
|
|
| Fair Value Measurements |
|
|
| Foreign exchange contracts |
$ 200
|
|
| 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 |
|
|
| Adjusted cost, Available-for-sale investments |
$ 81,068
|
|
| Unrealized Gains, available-for-sale investments |
2
|
|
| Unrealized Losses, available-for-sale investments |
(63)
|
|
| Fair value, Available-for-sale investments |
81,007
|
|
| Assets, Adjusted Cost |
|
$ 97,266
|
| Assets, Unrealized Gains |
|
2
|
| Assets, Unrealized Losses |
|
(49)
|
| Assets, Fair Value |
|
97,219
|
| Measured on a recurring basis | Cash and Cash Equivalents |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
29,530
|
29,187
|
| Measured on a recurring basis | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
37,761
|
53,523
|
| Measured on a recurring basis | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
13,716
|
14,509
|
| Measured on a recurring basis | Cash |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
7,593
|
|
| Fair value, Available-for-sale investments |
7,593
|
|
| Assets, Adjusted Cost |
|
13,077
|
| Assets, Fair Value |
|
13,077
|
| Measured on a recurring basis | Cash | Cash and Cash Equivalents |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
7,593
|
13,077
|
| Measured on a recurring basis | Level 1 |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
22,935
|
|
| Unrealized Losses, available-for-sale investments |
(2)
|
|
| Fair value, Available-for-sale investments |
22,933
|
|
| Assets, Adjusted Cost |
|
16,110
|
| Assets, Fair Value |
|
16,110
|
| Measured on a recurring basis | Level 1 | Cash and Cash Equivalents |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
21,937
|
16,110
|
| Measured on a recurring basis | Level 1 | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
996
|
|
| Measured on a recurring basis | Level 1 | Money market funds |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
21,937
|
|
| Fair value, Available-for-sale investments |
21,937
|
|
| Assets, Adjusted Cost |
|
16,110
|
| Assets, Fair Value |
|
16,110
|
| Measured on a recurring basis | Level 1 | Money market funds | Cash and Cash Equivalents |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
21,937
|
16,110
|
| Measured on a recurring basis | Level 1 | U.S. government notes |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
998
|
|
| Unrealized Losses, available-for-sale investments |
(2)
|
|
| Fair value, Available-for-sale investments |
996
|
|
| Measured on a recurring basis | Level 1 | U.S. government notes | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Assets, Fair Value |
996
|
|
| Measured on a recurring basis | Level 2 |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
50,540
|
68,079
|
| Unrealized Gains, available-for-sale investments |
2
|
2
|
| Unrealized Losses, available-for-sale investments |
(61)
|
(49)
|
| Fair value, Available-for-sale investments |
50,481
|
68,032
|
| Measured on a recurring basis | Level 2 | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
37,761
|
53,523
|
| Measured on a recurring basis | Level 2 | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
12,720
|
14,509
|
| Measured on a recurring basis | Level 2 | Asset-backed securities |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
6,739
|
4,458
|
| Unrealized Losses, available-for-sale investments |
(9)
|
(3)
|
| Fair value, Available-for-sale investments |
6,730
|
4,455
|
| Measured on a recurring basis | Level 2 | Asset-backed securities | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
6,730
|
4,455
|
| Measured on a recurring basis | Level 2 | Corporate bonds |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
39,195
|
54,321
|
| Unrealized Gains, available-for-sale investments |
2
|
2
|
| Unrealized Losses, available-for-sale investments |
(51)
|
(46)
|
| Fair value, Available-for-sale investments |
39,146
|
54,277
|
| Measured on a recurring basis | Level 2 | Corporate bonds | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
33,156
|
46,726
|
| Measured on a recurring basis | Level 2 | Corporate bonds | Long-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
5,990
|
7,551
|
| Measured on a recurring basis | Level 2 | Commercial paper |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
1,100
|
6,797
|
| Fair value, Available-for-sale investments |
1,100
|
6,797
|
| Measured on a recurring basis | Level 2 | Commercial paper | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
1,100
|
6,797
|
| Measured on a recurring basis | Level 2 | U.S. agency securities |
|
|
| Fair Value Measurements |
|
|
| Adjusted cost, Available-for-sale investments |
3,506
|
2,503
|
| Unrealized Losses, available-for-sale investments |
(1)
|
|
| Fair value, Available-for-sale investments |
3,505
|
2,503
|
| Measured on a recurring basis | Level 2 | U.S. agency securities | Short-term investments |
|
|
| Fair Value Measurements |
|
|
| Fair value, Available-for-sale investments |
$ 3,505
|
|
| 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
|