Segments and Related Information (Reconciliation of Consolidated Income before Income Taxes to EBITDA) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
EBITDA Reconciliation:
Income before income taxes	$ 107,579	$ 95,346	$ 314,330	$ 132,417
Interest expense, net	17,578	13,097	44,966	37,895
Depreciation and amortization	50,101	42,584	138,384	122,249
Consolidated EBITDA	$ 175,300	$ 151,000	$ 497,700	$ 292,600