Income Taxes (Components Of Income Before Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 788,878	$ 954,138	$ 1,101,427
Foreign	74,961	69,773	48,736
Income before provision for income taxes	$ 863,839	$ 1,023,911	$ 1,150,163