Stock-Based Compensation (Summary Of Stock Options) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning of year, Weighted-Average Exercise Price	$ 56.37	$ 51.07	$ 48.76
Granted, Weighted-Average Exercise Price	0.00	94.38	88.10
Issued pursuant to acquisitions, Weighted-Average Exercise Price	0.00	0.00	12.26
Exercised, Weighted-Average Exercise Price	49.78	45.57	40.52
Forfeited, Weighted-Average Exercise Price	80.92	72.07	70.15
Outstanding, end of year, Weighted-Average Exercise Price	59.17	56.37	51.07
Vested and Exercisable, end of year, Weighted-Average Exercise Price	$ 55.11	$ 51.80	$ 48.29
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of year, Options	3,136	3,986	4,932
Granted, Options	0	260	57
Issued pursuant to acquisitions, Options	0	0	8
Exercised, Options	(956)	(1,082)	(975)
Forfeited, Options	(10)	(28)	(36)
Outstanding, end of year, Options	2,170	3,136	3,986
Vested and Exercisable, end of year, Options	1,930	2,762	3,539
Outstanding, Weighted-Average Remaining Contractual Term (in years)	4 years 1 month 6 days	4 years 7 months 14 days	4 years 10 months 5 days
Vested and Exercisable, Weighted-Average Remaining Contractual Term (in years)	3 years 6 months 26 days	4 years 15 days	4 years 6 months 12 days
Outstanding, Aggregate Intrinsic Value	$ 191,895	$ 113,822	$ 165,131
Vested and Exercisable, Aggregate Intrinsic Value	$ 178,456	$ 112,379	$ 156,487