Segments and Related Information (Reconciliation of Consolidated Income before Income Taxes to EBITDA) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
EBITDA Reconciliation:
Income before income taxes	$ 159,959	$ 116,183	$ 215,100	$ 153,772
Interest expense, net	16,623	20,795	38,881	37,854
Depreciation and amortization	59,944	51,676	118,975	101,615
EBITDA	$ 236,500	$ 188,700	$ 373,000	$ 293,200