Segments and Related Information (Reconciliation of Consolidated Income (Loss) before Income Taxes to EBITDA) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
EBITDA Reconciliation:
Income (loss) before income taxes	$ 371,826	$ 225,819	$ (67,746)
Interest expense, net	61,011	50,734	48,055
Depreciation and amortization	188,049	164,915	169,662
EBITDA	$ 620,900	$ 441,500	$ 150,000