Leases (Details) $ in Thousands	1 Months Ended		9 Months Ended
	Nov. 30, 2018 USD ($)	Jan. 31, 2018 USD ($) Options	Sep. 30, 2019 USD ($) lease property item	Aug. 08, 2019	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Leases
Number of leases | lease			2
Number of expiration period | item			2
Number of leased properties | property			2
Lease term		8 years		9 years
Extended lease term		5 years
Number of options to renew lease | Options		1
Lessee, Operating Lease, Existence of Option to Extend [true false]		true
Initial annual base rent	$ 2,500	$ 3,800
Base rent incremental (as a percentage)	3.00%	3.00%
Benefit of the landlord secured by cash deposit	$ 600	$ 900
Tenant improvement allowance	9,200	9,400
Tenant improvement repayable to landlord	$ 2,000	$ 500
Construction-in-progress within property and equipment						$ 45,100
Operating lease, right-of-use-asset			$ 47,911		$ 1,751
Embedded lease contracts
Leases
Lease term			22 months
Lessee, Operating Lease, Existence of Option to Extend [true false]			false