Stock Option And Grant Plan (Summary Of Stock Options) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of year, Options	7,545	7,319	8,110
Granted, Options	1,109	1,104	1,204
Issued pursuant to apache Acquisition, Options	0	418	0
Exercised, Options	(1,464)	(1,179)	(1,924)
Forfeited, Options	(68)	(117)	(71)
Outstanding, end of year, Options	7,122	7,545	7,319
Vested and Exercisable, end of year, Options	4,094	4,251	4,214
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning of period, Weighted Average Exercise Price	$ 35.10	$ 29.92	$ 22.94
Granted, Weighted Average Exercise Price	$ 67.53	$ 58.50	$ 48.35
Issued pursuant to Apache acquisition, Weighted Average Exercise Price	$ 0.00	$ 18.66	$ 0.00
Exercised, Weighted Average Exercise Price	$ 21.85	$ 19.33	$ 11.92
Forfeited, Weighted Average Exercise Price	$ 36.90	$ 33.27	$ 32.40
Outstanding, end of period, Weighted Average Exercise Price	$ 42.85	$ 35.10	$ 29.92
Vested and Exercisable, end of period, Weighted Average Exercise Price	$ 33.91	$ 27.98	$ 23.11
Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 9 months 11 days	6 years 7 months 28 days	6 years 6 months 15 days
Vested and Exercisable, Weighted Average Remaining Contractual Term (in years)	5 years 5 months 23 days	5 years 2 months 12 days	5 years 1 month 28 days
Outstanding, Aggregate Intrinsic Value	$ 174,383	$ 168,837	$ 162,099
Vested and Exercisable, Aggregate Intrinsic Value	$ 136,851	$ 124,550	$ 122,022