Leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, net	$ (34,427)		$ (36,050)	$ (61,511)
Accrued expenses and other current liabilities	(13,724)		(8,271)	(10,908)
Lease financing obligations, net of current portion	0		0	$ (22,987)
Rent expense		$ 1,700
Cash payments	$ 2,300
Cash payments		2,500
Weighted average remaining lease term	7 years 4 months 24 days
Weighted average discount rate	5.60%
Sublease income	$ 500
Sublease income		$ 500
Adjustments Due to Adoption of New Leasing Standard
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, net			25,461
Accrued expenses and other current liabilities			2,637
Lease financing obligations, net of current portion			22,987
Adjustments Due to Adoption of New Leasing Standard | Capitalized facility leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, net			28,300
Accrued expenses and other current liabilities			1,800
Lease financing obligations, net of current portion			$ 23,000
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining lease terms	1 year
Lease renewal term	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining lease terms	11 years
Lease renewal term	5 years