Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	$ 17,060	$ 26,242
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	5,221	13,127
Significant Other Observable Inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	11,839	13,115
Significant Unobservable Inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	0	0
Money market funds (cash equivalents)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	5,221	13,127
Money market funds (cash equivalents) | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	5,221	13,127
Money market funds (cash equivalents) | Significant Other Observable Inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	0	0
Money market funds (cash equivalents) | Significant Unobservable Inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	0	0
Corporate notes and bonds
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	9,332	12,974
Corporate notes and bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	0	0
Corporate notes and bonds | Significant Other Observable Inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	9,332	12,974
Corporate notes and bonds | Significant Unobservable Inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	0	0
Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	2,507	141
Asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	0	0
Asset-backed securities | Significant Other Observable Inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	2,507	141
Asset-backed securities | Significant Unobservable Inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	$ 0	$ 0