Leases - Lease Expense and Other Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 6,401	$ 12,584
Amortization of right-of-use assets	24	48
Interest on lease liabilities	32	65
Short-term lease cost	35	80
Sublease income	(97)	(192)
Total lease cost	6,395	12,585
(Gain)/loss on right-of-use asset impairment-Operating leases	1,734	2,551
Operating cash flows from operating leases	6,045	11,347
Operating cash flows from finance leases	33	66
Financing cash flows from finance leases	31	62
Right-of-use assets obtained in exchange for lease obligations - operating leases	2,342	4,784
Right-of-use assets obtained in exchange for lease obligations - finance leases	$ 0	$ 0