Lease Commitments - Supplemental Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 9,098	$ 17,181
Operating cash flows from finance leases	55	109
Financing cash flows from finance leases	(193)	(389)
Leased assets obtained in exchange for new finance lease liabilities	$ 20	$ 72