Stock-Based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of stock options granted under Plan	10 years
Vesting period, generally, for stock options granted under the plan	3 years
Share based compensation costs	$ 2,800,000	$ 2,000,000	$ 2,700,000
Tax benefit of share-based compensation	1,100,000	800,000	1,100,000
Forfeiture rate assumed (in hundredths)	7.50%	7.31%
Weighted average grant date fair value for stock options granted (in dollars per share)	$ 15.83	$ 10.74	$ 11.03
Weighted average grant date fair value for stock options vested (in dollars per share)	$ 10.29	$ 8.57	$ 7.58
Total intrinsic value of stock options exercised	10,000,000	3,300,000	1,700,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit	$ 19.855
Exercise price range, upper limit	$ 42.415
Options Outstanding [Abstract]
Number outstanding at end of period (in shares)	1,131,415
Weighted average remaining contractual term (in years)	4 years 9 months 18 days
Weighted average exercise price (in dollars per share)	$ 32.42
Options Exercisable [Abstract]
Number exercisable at end of period (in shares)	758,014
Weighted average exercise price (in dollars per share)	$ 29.67
$19.855 to $24.753 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit	$ 19.855
Exercise price range, upper limit	$ 24.753
Options Outstanding [Abstract]
Number outstanding at end of period (in shares)	140,018
Weighted average remaining contractual term (in years)	6 years 1 month 6 days
Weighted average exercise price (in dollars per share)	$ 23.13
Options Exercisable [Abstract]
Number exercisable at end of period (in shares)	140,018
Weighted average exercise price (in dollars per share)	$ 23.13
$26.257 to $29.665 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit	$ 26.257
Exercise price range, upper limit	$ 29.665
Options Outstanding [Abstract]
Number outstanding at end of period (in shares)	50,828
Weighted average remaining contractual term (in years)	2 years
Weighted average exercise price (in dollars per share)	$ 27.15
Options Exercisable [Abstract]
Number exercisable at end of period (in shares)	48,322
Weighted average exercise price (in dollars per share)	$ 27.16
$30.097 to $34.657 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit	$ 30.097
Exercise price range, upper limit	$ 42.415
Options Outstanding [Abstract]
Number outstanding at end of period (in shares)	940,569
Weighted average remaining contractual term (in years)	6 years 4 months 24 days
Weighted average exercise price (in dollars per share)	$ 34.09
Options Exercisable [Abstract]
Number exercisable at end of period (in shares)	569,674
Weighted average exercise price (in dollars per share)	$ 31.49
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (years)	6 years 10 months 24 days	6 years 10 months 24 days	6 years 3 months 18 days
Interest rate (in hundredths)	1.22%	1.36%	2.46%
Volatility (in hundredths)	37.82%	31.26%	30.93%
Expected dividend yield (in hundredths)	0.48%	0.31%	0.31%
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	1,395,520
Granted (in shares)	239,770
Exercised (in shares)	(501,222)
Forfeited/canceled (in shares)	(2,653)
Balance, end of year (in shares)	1,131,415	1,395,520
Exercisable, end of year (in shares)	758,014
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 28.31
Granted (in dollars per share)	$ 41.42
Exercised (in dollars per share)	$ 25.26
Forfeited/canceled (in dollars per share)	$ 37.24
Balance, end of year (in dollars per share)	$ 32.42	$ 28.31
Exercisable, end of year (in dollars per share)	$ 29.67
Weighted Average Remaining Contractual Life [Abstract]
Outstanding options, end of year (in years)	6 years 1 month 28 days
Exercisable options, end of year (in years)	4 years 11 months 12 days
Aggregate Intrinsic Value [Abstract]
Outstanding options, end of year	31,283,000
Exercisable options, end of year	23,046,000
Closing stock price on last business day of the period (in dollars per share)	$ 60.07
Weighted average intrinsic value of options exercised (in dollars per share)	$ 20.03	$ 10.11	$ 7.15
Unrecognized stock-based compensation expense	2,400,000
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized	3 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation costs	3,900,000	3,400,000	4,600,000
Aggregate Intrinsic Value [Abstract]
Unrecognized stock-based compensation expense	3,400,000
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized	3 years
Restricted Stock [Roll Forward]
Balance, beginning of year (in shares)	183,660	252,024	300,540
Granted (in shares)	112,225	123,446	136,978
Vested (in shares)	(107,956)	(102,424)	(94,246)
Canceled (in shares)	(2,357)	(89,386)	(91,248)
Balance, end of year (in shares)	185,572	183,660	252,024
Weighted Average Grant Date Fair Value [Abstract]
Balance, beginning of year (in dollars per share)	$ 31.25	$ 27.21	$ 23.60
Granted (in dollars per share)	$ 41.44	$ 32.04	$ 32.08
Vested (in dollars per share)	$ 30.71	$ 25.90	$ 31.99
Canceled (in dollars per share)	$ 36.39	$ 27.08	$ 30.22
Balance, end of year (in dollars per share)	$ 37.65	$ 31.25	$ 27.21
Reversals of compensation expense related to restricted stock forfeitures	$ 100,000	$ 0	$ 100,000
Nonvested Stock Options [Member]
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	327,086
Granted (in shares)	239,770
Vested (in shares)	(190,802)
Forfeited/canceled (in shares)	(2,653)
Balance, end of year (in shares)	373,401
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 31.17
Granted (in dollars per share)	$ 41.42
Vested (in dollars per share)	$ 30.57
Forfeited/canceled (in dollars per share)	$ 37.24
Balance, end of year (in dollars per share)	$ 38.01