Income Taxes (Schedule Of Effective Reconciliation Of The U.S. Statutory Federal Income Tax Rates) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Tax provision at statutory rate on income before income taxes	$ 171,506	$ 151,380	$ 115,040
State income taxes, net of federal benefit	17,097	14,120	12,083
Meals and entertainment disallowance	1,035	959	872
Tax credits	(3,036)	(1,307)	(5,422)
Other, net	(1,275)	(152)	0
Total provision for income taxes	$ 185,327	$ 165,000	$ 122,573