Share-Based Compensation Level 4 (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total pretax employee share-based compensation expense included in net income	$ 14,103,000	$ 15,029,000	$ 15,626,000
Income tax benefit related to share-based compensation included in net income	$ 3,417,000	$ 3,842,000	$ 3,998,000
Stock Option Plan Exercise Range 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding				2,581,498
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance				$ 21.70
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Exercisable				2,581,498
Share-based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price				$ 21.70
Stock Option Plan Exercise Range 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding				1,419,762
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance				$ 29.25
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Exercisable				1,419,762
Share-based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price				$ 29.25
Stock Option Plan Exercise Range 3 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding				1,946,865
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance				$ 39.54
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Exercisable				1,099,983
Share-based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price				$ 38.68
Stock Option Plan Exercise Range 4 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding				963,940
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance				$ 50.82
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Exercisable				0
Share-based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price				$ 0
Stock Option Plan Exercise Range 5 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding				6,912,065
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance				$ 32.34
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Exercisable				5,101,243
Share-based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price				$ 27.46
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	1.70%	1.70%	1.80%
Risk-free interest rate	1.40%	2.50%	2.40%
Expected holding period		4 years	4 years
Total pretax employee share-based compensation expense included in net income	$ 5,668,000	$ 6,314,000	$ 6,648,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at beginning of period	7,309,446
Options outstanding at beginning of period, weighted average exercise price	$ 27.53
Granted	963,940
Granted, Weighted Average Exercise Price	$ 50.82
Exercised	(1,361,321)
Exercised, Weighted Average Exercise Price	$ 19.59
Options outstanding at end of period	6,912,065	7,309,446
Options outstanding at end of period, weighted average exercise price	$ 32.34	$ 27.53
Options exercisable at December 31, 2011	6,912,065	7,309,446		6,912,065
Options exercisable at December 31, 2011, Weighted Average Exercise Price	$ 32.34	$ 27.53		$ 32.34
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number				5,101,243
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price				$ 27.46
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Expected volatility	18.00%	19.80%	18.50%
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 9 months 18 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total pretax employee share-based compensation expense included in net income	$ 5,568,000	$ 6,000,000	$ 6,063,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested restricted shares at beginning of period	288,065
Nonvested restricted shares at beginning of period, weighted average grant date fair value	$ 38.09
Granted	113,872
Granted, Weighted Average Grant Date Fair Value	$ 50.82	$ 42.73	$ 37.50
Vested	(158,408)
Vested, Weighted Average Grant Date Fair Value	$ 35.82
Nonvested restricted shares at end of period	243,529	288,065
Nonvested restricted shares at end of period, weighted average grant date fair value	$ 45.52	$ 38.09
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 5,674,000	$ 6,718,000	$ 5,702,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested	$ 2,100,000	3,724,000	3,578,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 9 months 18 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total pretax employee share-based compensation expense included in net income	$ 2,867,000	$ 2,715,000	$ 2,862,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested restricted shares at beginning of period	151,452
Nonvested restricted shares at beginning of period, weighted average grant date fair value	$ 36.79
Granted	67,151
Granted, Weighted Average Grant Date Fair Value	$ 48.89	$ 40.91	$ 35.89
Vested	(78,453)
Vested, Weighted Average Grant Date Fair Value	$ 34.69
Nonvested restricted shares at end of period	135,308	151,452
Nonvested restricted shares at end of period, weighted average grant date fair value	$ 43.83	$ 36.79
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 2,722,000	$ 2,827,000	$ 1,946,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(4,842)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 41.70
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested	$ 1,004,000	1,432,000	970,000
Performance Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.11%
Total pretax employee share-based compensation expense included in net income	$ 8,600,000	$ 6,100,000	$ 3,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Granted	112,762	125,546	161,864
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested restricted shares at beginning of period, weighted average grant date fair value	$ 40.70
Nonvested restricted shares at end of period, weighted average grant date fair value	$ 49.10	$ 40.70
Expected volatility	38.00%
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 6 months