Leases - Schedule of Cumulative Effects (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets
Other current assets	$ 7,777	$ 4,291	$ 4,103
Property and equipment, net	34,427	36,050	61,511
Operating lease right-of-use assets	40,545	42,010	0
Other assets	7,112	7,375	7,228
Liabilities
Operating lease liabilities, current	6,849	6,498	0
Accrued expenses and other current liabilities	13,724	8,271	10,908
Lease financing obligations, net of current portion	0	0	22,987
Operating lease liabilities, net of current portion	41,601	43,351	0
Other liabilities	5,655	5,639	9,290
Stockholders’ Equity
Accumulated deficit	$ (391,537)	(377,172)	(373,482)
Adjustments Due to Adoption of New Leasing Standard
Assets
Other current assets		188
Property and equipment, net		(25,461)
Operating lease right-of-use assets		42,010	0
Other assets		147
Liabilities
Operating lease liabilities, current		6,498	$ 0
Accrued expenses and other current liabilities		(2,637)
Lease financing obligations, net of current portion		(22,987)
Operating lease liabilities, net of current portion		43,351
Other liabilities		(3,651)
Stockholders’ Equity
Accumulated deficit		$ (3,690)