Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies [Abstract]
Total rental expense under operating leases	$ 22,658	$ 29,039	$ 27,431
Future minimum lease payments for operating leases [Abstract]
2019	18,911
2020	14,955
2021	10,972
2022	8,790
2023	7,490
Thereafter	23,155
Environmental Matters
Accrued environmental liabilities	12,190
Accrued environmental liabilities, current	5,438
Accrued environmental liabilities, noncurrent	6,752
Estimated purchase commitments [Abstract]
2019	40,697
2020	$ 16,792