Equity and Cash Incentive Program (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assumptions used in determining fair value [Abstract]
Performance share requisite performance and service period (in years)	3Y
Stock-based compensation expense [Abstract]
Pre-tax compensation expense	$ 25,991	$ 21,207	$ 17,158
Tax benefit	(9,097)	(7,422)	(6,005)
Total stock-based compensation expense, net of tax	16,894	13,785	11,153
Shares granted to directors [Abstract]
Aggregate shares granted (in shares)	20,929	20,853	21,549
Shares withheld to satisfy tax obligations (in shares)	(562)	(574)	(6,823)
Net shares granted (in shares)	20,367	20,279	14,726
2005 Equity and Cash Incentive [Member]
2005 Equity and Cash Incentive Plan [Abstract]
Shares reserved for grants and incentive stock options (in shares)	20,000,000
Shares available for grant as restricted stock or performance shares (in shares)	2,000,000
Vesting period for all stock options or stock appreciation rights, minimum (in years)	3 Y
Stock Compensation Plan [Member]
2005 Equity and Cash Incentive Plan [Abstract]
Expiration period of employee share based compensation plans (in years)	10 Y
SARs and Stock Options [Member]
Assumptions used in determining fair value [Abstract]
Risk-free interest rate (in hundredths)	2.68%	2.77%	2.06%
Dividend yield (in hundredths)	1.70%	2.33%	3.23%
Expected life (in years)	5.8	6.0	6.5
Volatility (in hundredths)	33.56%	31.93%	30.47%
Option grant price (in dollars per share)	$ 66.59	$ 42.88	$ 29.45
Fair value of options granted (in dollars per share)	$ 20.13	$ 11.66	$ 6.58
Weighted average exercise price [Abstract]
Stock Options, weighted average exercise price, granted (in dollars per share)	$ 66.59	$ 42.88	$ 29.45
Weighted average remaining contractual life [Abstract]
Unrecognized compensation expense	27,570
Weighted average period for recognizing the unrecognized cost (in years)	1.7
Cash received by the company for granting stock options	26,519
Performance Share Awards [Member]
Assumptions used in determining fair value [Abstract]
Risk-free interest rate (in hundredths)	1.34%	1.37%	1.30%
Dividend yield (in hundredths)	1.61%	2.38%	2.93%
Expected life (in years)	2.9	2.9	2.7
Volatility (in hundredths)	40.48%	39.98%	39.57%
Fair value of performance award (in dollars per share)	$ 91.41	$ 57.49	$ 35.79
Number of companies in peer group	38
Performance share requisite performance and service period (in years)	3
Share Awards [Roll forward]
Granted (in shares)	44,751	68,446	75,892
Vested (in shares)	(72,151)
Forfeited (in shares)	(2,855)
Forfeited (in shares)	(2,855)
Unvested, end of period (in shares)	113,197	143,452
Weighted average grant date fair value unvested, beginning of period (in dollars per share)	$ 46.14
Weighted average grant date fair value, granted (in dollars per share)	$ 91.41	$ 57.49	$ 35.79
Weighted average grant date fair value, vested (in dollars per share)	$ 35.79
Weighted average grant date fair value, forfeited (in dollars per share)	$ 35.79
Weighted average grant date fair value, end of period (in dollars per share)	$ 57.23	$ 46.14
Unvested, beginning of period (in shares)	143,452
Granted (in shares)	44,751	68,446	75,892
Weighted average remaining contractual life [Abstract]
Unrecognized compensation expense	3,667
Weighted average period for recognizing the unrecognized cost (in years)	1.6
Additional Information [Abstract]
Percentage of original target grant actual number of shares awarded, low range (in hundredths)	0.00%
Percentage of original target grant actual number of shares awarded, high range (in hundredths)	200.00%
Percentage of original target awards vested are expected to be paid (in hundredths)	105.00%
Stock Appreciation Rights (SARs) [Member]
Share Awards [Roll forward]
Unvested, beginning of period (in shares)	9,432,013
Granted (in shares)	1,524,329	2,304,574	2,825,701
Forfeited (in shares)	(308,882)
Forfeited (in shares)	(308,882)
Exercised (in shares)	(1,253,826)
Unvested, end of period (in shares)	9,393,634	9,432,013
Exercisable at end of period (in shares)	3,302,555
Granted (in shares)	1,524,329	2,304,574	2,825,701
Weighted average exercise price [Abstract]
Weighted average exercise price, outstanding, beginning of period (in dollars per share)	$ 40.63
Weighted average exercise price, granted (in dollars per share)	$ 66.59
Weighted average exercise price, forfeited (in dollars per share)	$ 42.03
Weighted average exercise price, exercised (in dollars per share)	$ 45.54
Weighted average exercise price, outstanding, end of period (in dollars per share)	$ 44.14	$ 40.63
Weighted average exercise price, exercisable, end of period (in dollars per share)	$ 45.92
Aggregate intrinsic value [Abstract]
Aggregate intrinsic value, exercised	24,322
Aggregate intrinsic value, outstanding, end of period	143,317
Aggregate intrinsic value, total exercisable	40,051
Weighted average remaining contractual life [Abstract]
Weighted average remaining contractual life, outstanding ,end of period (in years)	6.38
Weighted average remaining contractual life, total exercisable, end of period (in years)	4.35
Fair value of stock appreciation rights which became exercisable during the year	21,202
Stock Appreciation Rights (SARs) [Member] | Range One [Member]
Additional Information [Abstract]
Outstanding exercise price range, lower range limit (in dollars per share)	$ 29.45
Outstanding exercise price range, upper range limit (in dollars per share)	$ 35.50
Outstanding, number, end of period (in shares)	2,490,684
Outstanding, weighted average exercise price, end of period (in dollars per share)	$ 29.52
Outstanding, weighted average remaining life in years, end of period (in years)	6.28
Exercisable, number, end of period (in shares)	0
Exercisable, weighted average exercise price, end of period (in dollars per share)	$ 0
Exercisable, weighted average remaining life in years, end of period (in years)	0
Stock Appreciation Rights (SARs) [Member] | Range Two [Member]
Additional Information [Abstract]
Outstanding exercise price range, lower range limit (in dollars per share)	$ 42.30
Outstanding exercise price range, upper range limit (in dollars per share)	$ 46.00
Outstanding, number, end of period (in shares)	4,378,418
Outstanding, weighted average exercise price, end of period (in dollars per share)	$ 43.33
Outstanding, weighted average remaining life in years, end of period (in years)	6.09
Exercisable, number, end of period (in shares)	2,255,049
Exercisable, weighted average exercise price, end of period (in dollars per share)	$ 43.75
Exercisable, weighted average remaining life in years, end of period (in years)	4.47
Stock Appreciation Rights (SARs) [Member] | Range Three [Member]
Additional Information [Abstract]
Outstanding exercise price range, lower range limit (in dollars per share)	$ 50.60
Outstanding exercise price range, upper range limit (in dollars per share)	$ 66.59
Outstanding, number, end of period (in shares)	2,524,532
Outstanding, weighted average exercise price, end of period (in dollars per share)	$ 59.96
Outstanding, weighted average remaining life in years, end of period (in years)	6.96
Exercisable, number, end of period (in shares)	1,047,506
Exercisable, weighted average exercise price, end of period (in dollars per share)	$ 50.60
Exercisable, weighted average remaining life in years, end of period (in years)	4.11
Stock Options [Member]
Assumptions used in determining fair value [Abstract]
Option grant price (in dollars per share)	$ 0
Share Awards [Roll forward]
Stock Options outstanding, beginning of period (in shares)	2,899,135
Stock Options granted (in shares)	0
Stock options forfeited (in shares)	(77,699)
Stock Options exercised (in shares)	(878,342)
Stock Options outstanding, end of period (in shares)	1,943,094
Stock Options exercisable at end of period (in shares)	1,943,094
Weighted average exercise price [Abstract]
Stock Options, weighted average exercise price, outstanding , beginning of period (in dollars per share)	$ 36.79
Stock Options, weighted average exercise price, granted (in dollars per share)	$ 0
Stock Options, weighted average exercise price, forfeited (in dollars per share)	$ 38.75
Stock Options, weighted average exercise price, exercised (in dollars per share)	$ 36.24
Stock Options, weighted average exercise price, outstanding, end of period (in dollars per share)	$ 36.96
Stock Options, weighted average exercise price, exercisable, end of period (in dollars per share)	$ 36.96
Aggregate intrinsic value [Abstract]
Stock Options, aggregate intrinsic value, exercised	24,726
Stock Options, aggregate intrinsic value, outstanding, end of period	40,989
Stock Options, aggregate intrinsic value, total exercisable	$ 40,989
Weighted average remaining contractual life [Abstract]
Stock Options, weighted average remaining contractual life, outstanding ,end of period (in years)	2.11
Stock Options, weighted average remaining contractual life, total exercisable, end of period (in years)	2.11
Stock Options [Member] | Range One [Member]
Additional Information [Abstract]
Outstanding exercise price range, lower range limit (in dollars per share)	$ 24.50
Outstanding exercise price range, upper range limit (in dollars per share)	$ 31.00
Outstanding, number, end of period (in shares)	294,397
Outstanding, weighted average exercise price, end of period (in dollars per share)	$ 24.53
Outstanding, weighted average remaining life in years, end of period (in years)	1.12
Exercisable, number, end of period (in shares)	294,397
Exercisable, weighted average exercise price, end of period (in dollars per share)	$ 24.53
Exercisable, weighted average remaining life in years, end of period (in years)	1.12
Stock Options [Member] | Range Two [Member]
Additional Information [Abstract]
Outstanding exercise price range, lower range limit (in dollars per share)	$ 33.00
Outstanding exercise price range, upper range limit (in dollars per share)	$ 39.00
Outstanding, number, end of period (in shares)	1,052,031
Outstanding, weighted average exercise price, end of period (in dollars per share)	$ 38.00
Outstanding, weighted average remaining life in years, end of period (in years)	2.41
Exercisable, number, end of period (in shares)	1,052,031
Exercisable, weighted average exercise price, end of period (in dollars per share)	$ 38.00
Exercisable, weighted average remaining life in years, end of period (in years)	2.41
Stock Options [Member] | Range Three [Member]
Additional Information [Abstract]
Outstanding exercise price range, lower range limit (in dollars per share)	$ 39.40
Outstanding exercise price range, upper range limit (in dollars per share)	$ 43.00
Outstanding, number, end of period (in shares)	596,666
Outstanding, weighted average exercise price, end of period (in dollars per share)	$ 41.24
Outstanding, weighted average remaining life in years, end of period (in years)	2.06
Exercisable, number, end of period (in shares)	596,666
Exercisable, weighted average exercise price, end of period (in dollars per share)	$ 41.24
Exercisable, weighted average remaining life in years, end of period (in years)	2.06
Restricted Stock Units (RSUs) [Member]
Additional Information [Abstract]
Period for which the sale or transfer of shares are restricted (in years)	two or three year period
Number of restricted stock grants (in shares)	55,200	15,500