Share-Based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Grant Date Fair Value Assumptions [Abstract]
Share-based compensation	$ 8,150,000	$ 8,465,000	$ 8,233,000
Stock Options [Member]
Stock option activity [Roll Forward]
Beginning balance (in shares)	3,944,191
Granted (in shares)	236,700
Exercised (in shares)	780,485	986,110	958,509
Forfeited (in shares)	7,125
Ending balance (in shares)	3,393,281	3,944,191
Exercisable (In Shares)	1,963,668
Stock option weighted average exercise price [Abstract]
Beginning balance (in dollars per share)	$ 26.33
Granted (in dollars per share)	$ 45.62
Exercised (in dollars per share)	$ 26.04
Forfeited (in dollars per share)	$ 27.47
Ending balance (in dollars per share)	$ 27.74	$ 26.33
Exercisable at end of period (in dollars per share)	$ 27.23
Weighted Average Remaining Contractual Term [Abstract]
Weighted average remaining contractual term of shares outstanding (in years)	5 years 0 months 7 days
Weighted average remaining contractual term of shares exercisable at end of period (in years)	3 years 5 months 19 days
Aggregate Intrinsic Value [Abstract]
Ending balance	103,141,413
Exercisable at end of period	60,700,817
Cash Proceeds and Tax Benefits [Abstract]
Exercised (in shares)	780,485	986,110	958,509
Cash proceeds	20,323,000	19,221,000	12,173,000
Intrinsic value of options exercised	19,273,000	19,383,000	13,868,000
Tax benefits realized	7,364,000	7,418,000	5,409,000
Grant Date Fair Value Assumptions [Abstract]
Expected volatility (in hundredths)	38.70%	38.60%	37.90%
Expected term (in years)	7 years 6 months 10 days	7 years 7 months 6 days	7 years 9 months 18 days
Risk-free interest rate (in hundredths)	1.51%	1.61%	3.10%
Expected dividend yield (in hundredths)	1.50%	2.00%	2.00%
Grant date fair value (in dollars per share)	$ 16.42	$ 12.66	$ 8.97
Share-based compensation	3,746,000	4,304,000	4,497,000
Recognized tax benefits	1,431,000	1,647,000	1,721,000
Unamortized compensation expense	3,500,000
Expense recognition over weighted average period (in years)	2 years 0 months 21 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	528,938
Grant Date Fair Value Assumptions [Abstract]
Share-based compensation	4,103,000	3,873,000	3,507,000
Unamortized compensation expense	2,700,000
Expense recognition over weighted average period (in years)	1 year 8 months 12 days
Restricted stock awards [Roll Forward]
Beginning balance (in shares)	516,186
Granted (at market price) (in shares)	80,454
Vested (in shares)	102,536	69,580	32,856
Forfeited (in shares)	3,840
Ending balance (in shares)	490,264	516,186
Restricted stock awards weighted average grant date fair value [Abstract]
Beginning balance (in dollars per share)	$ 23.36
Granted (at market price) (in dollars per share)	$ 46.31
Vested (in dollars per share)	$ 23.94
Forfeited (in dollars per share)	$ 25.87
Ending balance (in dollars per share)	$ 26.98	$ 23.36
Vested (in shares)	102,536	69,580	32,856
Fair value of restricted stock awards vested	4,544,000	2,338,000	812,000
ESPP Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased under the ESPP (in shares)	26,644	31,275	37,653
Grant Date Fair Value of most recent ESPP Purchase (per share)	$ 10.64
Grant Date Fair Value Assumptions [Abstract]
Share-based compensation	$ 300,000	$ 300,000	$ 200,000
LTIP 2007 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares allocated for issuance (in shares)	5,415,000
Number of shares originally allocated for issuance (in shares)	1,515,000
Shares available for grant	1,654,205
LTIP 2002 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares allocated for issuance (in shares)	2,700,000
Number of shares originally allocated for issuance (in shares)	1,575,000
Director plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares allocated for issuance (in shares)	1,350,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares allocated for issuance (in shares)	956,250
Discounted percentage rate offered under the employee stock purchase plan (in hundredths)	85.00%