Accounting Policies (Summary Of The Most Significant Impacts Of The New Accounting Guidance) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase in operating activities	$ 31,274	$ 26,990
Decrease in financing activities	(1,313)	2,562
Accounting Standards Update 2016-09 [Member]
Effective Income Tax Rate Reconciliation, Deduction, Amount	$ 11,200
Weighted Average Number Diluted Shares Outstanding Adjustment	450,000
Accounting Standards Update 2016-09 [Member] | Tax Benefits Related To Share-based Payments At Settlement Classified As Operating Cash Flows Instead Of Financing Cash Flows [Member]
Increase in operating activities	$ 11,200
Decrease in financing activities	11,200
Accounting Standards Update 2016-09 [Member] | Cash Payments To Tax Authorities For Shares Withheld To Meet Tax Withholding Requirements On Restricted Stock Units Are Classified As Financing Cash Flow Instead Of Operating Cash Flow [Member]
Increase in operating activities	7,300	3,800
Decrease in financing activities	$ 7,300	$ 3,800