Leases - Lease Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lease Cost
Operating lease cost	$ 2,136	$ 4,769
Short-term lease cost	20	116
Variable lease cost	624	1,554
Sublease income	(270)	(639)
Total lease cost	2,510	5,800
Operating Leases
Operating lease, right-of-use-asset	47,911	47,911	$ 1,751
Operating lease liabilities	6,998	6,998	616	$ 4,502
Operating lease liabilities, net of current portion	$ 41,439	$ 41,439	$ 1,226	$ 41,441
Weighted average remaining lease term - operating leases	7 years 8 months 12 days	7 years 8 months 12 days
Weighted-average discount rate - operating leases	7.58%	7.58%