Income Taxes Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net loss before income taxes:
Net loss before income taxes	$ (74,224)	$ (48,133)	$ (31,148)
Current:
United States	139	0	0
Other	0	0	0
Current Income Tax Expense (Benefit)	139	0	0
Deferred:
United States	0	0	0
Other	0	0	0
Deferred Income Tax Expense (Benefit)	0	0	0
Income Tax Expense (Benefit)	$ 139	$ 0	$ 0
Effective tax rate	(0.19%)	0.00%	0.00%
United States
Net loss before income taxes:
Net loss before income taxes	$ (59,211)	$ (48,133)	$ (31,148)
Other
Net loss before income taxes:
Net loss before income taxes	$ (15,013)	$ 0	$ 0