Fair Value of Financial Instruments (Summary of Carrying Amounts and Estimated Fair Values of Long-Term Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, excluding unamortized debt issuance costs and discounts, Carrying Amount	$ 1,229,418	$ 1,229,011
Total debt, excluding unamortized debt issuance costs and discounts, Estimated Fair Value	1,179,696	1,206,065
ABL Credit Facility, maturing 2021 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, excluding unamortized debt issuance costs and discounts, Carrying Amount	16,000	14,000
Total debt, excluding unamortized debt issuance costs and discounts, Estimated Fair Value	16,000	14,000
Senior Notes, maturing 2023 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, excluding unamortized debt issuance costs and discounts, Carrying Amount	400,000	400,000
Total debt, excluding unamortized debt issuance costs and discounts, Estimated Fair Value	361,132	382,984
Other debt [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, excluding unamortized debt issuance costs and discounts, Carrying Amount	24,038	24,260
Total debt, excluding unamortized debt issuance costs and discounts, Estimated Fair Value	24,038	24,260
Senior Credit Facility [Member] | Revolving Credit Facility, maturing 2021 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, excluding unamortized debt issuance costs and discounts, Carrying Amount	0	0
Total debt, excluding unamortized debt issuance costs and discounts, Estimated Fair Value	0	0
Senior Credit Facility [Member] | Term Loan Facility, maturing 2022 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, excluding unamortized debt issuance costs and discounts, Carrying Amount	789,380	790,751
Total debt, excluding unamortized debt issuance costs and discounts, Estimated Fair Value	$ 778,526	$ 784,821