Segments and Related Information (Reconciliation of Consolidated Income before Income Taxes to EBITDA) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
EBITDA Reconciliation:
Income before income taxes	$ 37,589	$ 67,985
Interest expense, net	17,058	12,597
Depreciation and amortization	49,940	42,904
Consolidated EBITDA	$ 104,600	$ 123,500