Leases - Lease Cost (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 11,738	$ 24,230
Amortization of right-of-use assets	256	512
Interest on lease liabilities	68	181
Total finance lease cost	324	693
Short-term lease cost	1,640	3,555
Total Lease Cost	13,702	28,478
Operating cash flows for operating leases	12,400	25,016
Operating cash flows for finance leases	68	181
Financing activities for finance leases	396	790
Right-of-use assets obtained in exchange for new operating lease liabilties	$ 3,154	$ 6,318
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 4 months 24 days	3 years 4 months 24 days
Weighted average discount rate, operating leases	4.74%	4.74%
Weighted average discount rate, finance leases	8.27%	8.27%