Fair Value Measurements - Schedule of Fair Value of Company's Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets
Total financial assets	$ 107,853	$ 111,325
Level 1
Assets
Total financial assets	14,027	45,937
Level 2
Assets
Total financial assets	93,826	65,388
Money Market Funds
Assets
Total financial assets	14,027	45,937
Money Market Funds | Level 1
Assets
Total financial assets	14,027	45,937
U.S. Government Securities
Assets
Total financial assets	32,909	16,490
U.S. Government Securities | Level 2
Assets
Total financial assets	32,909	16,490
Corporate Notes
Assets
Total financial assets	27,600	23,927
Corporate Notes | Level 2
Assets
Total financial assets	27,600	23,927
Commercial Paper
Assets
Total financial assets	33,317	24,971
Commercial Paper | Level 2
Assets
Total financial assets	$ 33,317	$ 24,971