Income Taxes - Reconciliation of Income Taxes at Statutory Rate (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory rate	34.00%	34.00%	34.00%
State tax credit (expense), net of federal benefit	1.40%	(1.50%)	5.60%
Foreign tax expense	(1.90%)	(3.70%)	(3.30%)
Change in valuation allowance	(28.60%)	(21.10%)	(34.60%)
Federal R&D Credit	2.60%	2.70%	6.90%
Unrecognized tax benefit	(1.80%)	(0.70%)	(4.50%)
Return to provision reconciliation	(1.20%)	(0.00%)	(2.80%)
Other, net	(1.90%)	(1.20%)	(2.10%)
Effective tax rate	2.60%	8.50%	(0.80%)