Leases - Lease Cost (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 11,611	$ 35,841
Amortization of right-of-use assets	256	768
Interest on lease liabilities	77	254
Total finance lease cost	333	1,022
Short-term lease cost	1,673	5,228
Total lease cost	13,617	42,091
Operating cash flows for operating leases	12,091	37,107
Operating cash flows for finance leases	77	254
Financing activities for finance leases	406	1,197
Right-of-use assets obtained in exchange for new operating lease liabilties	$ 2,335	$ 8,653
Weighted average remaining lease term, operating leases	7 years 3 months 18 days	7 years 3 months 18 days
Weighted average remaining lease term, finance leases	3 years 1 month 6 days	3 years 1 month 6 days
Weighted average discount rate, operating leases	4.74%	4.74%
Weighted average discount rate, finance leases	8.27%	8.27%