Accounts Payable and Accrued Expenses - Components of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accounts payable	$ 434,827	$ 424,140
Payroll and benefits, including incentive compensation	57,164	62,551
Health insurance, workers’ compensation and other insurance costs	58,706	60,068
Customer rebates	41,266	38,571
Other accrued liabilities	107,698	85,740
Total	$ 699,661	$ 671,070