Commitments and Contingencies - Reconciliation of Right-of-use Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets
Right-of-use assets, operating leases, net	$ 25,240		$ 0
Right-of-use assets - finance leases, net	384	$ 500	0
Liabilities
Operating lease, liability	26,830		0
Finance lease, liability	$ 183	300	$ 0
Accounting Standards Update 2016-02 [Member]
Assets
Right-of-use assets, operating leases, net		26,617
Right-of-use assets - finance leases, net		493
Liabilities
Operating lease, liability		27,562
Finance lease, liability		$ 302