Stock Based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock-Based Compensation (Details) [Line Items]
Tax benefits from stock option exercises	$ 406,000	$ 4,348,000	$ 7,036,000
Stock-based compensation expense	6,456,000	8,366,000	4,471,000
Stock-based compensation expense, net of tax	4,000,000	5,300,000	2,800,000
Vesting % of performance based restricted stock units, maximum	200.00%
Exercise period of options once vested	10 years
Restricted Stock Unit Activity (Table Details) [Abstract]
Number of nonvested restricted stock units outstanding	516,672	440,185
Granted	259,484
Vested	(149,669)
Forfeited	(33,328)
Weighted average grant date fair value, outstanding	$ 32.69	$ 28.96
Weighted average grant date fair value, granted	$ 32.70
Weighted average grant date fair value, vested	$ 21.66
Weighted average grant date fair value, forfeited	$ 32.97
Stock Option Activity (Table Details) [Abstract]
Number of awards outstanding	2,331,157	2,260,410
Granted	760,322	733,297	770,245
Exercised	(478,652)
Forfeited	(210,923)
Exercisable	863,893
Weighted Average Exercise Price [Abstract]
Equity awards outstanding	$ 31.36	$ 28.57
Granted	$ 36.05
Exercised	$ 24.93
Forfeited	$ 32.94
Exercisable	$ 26.13
Weighted Average Remaining Contractual Life [Abstract]
Equity awards outstanding	7 years 2 months 18 days
Exercisable	5 years 1 month 8 days
Aggregate Intrinsic Value [Abstract]
Equity awards outstanding	8,772,000
Exercised	5,800,000	7,500,000	24,100,000
Exercisable	6,905,000
Assumptions Used in Fair Value Calculation of Stock Options (Table Details) [Abstract]
Valuation method used	Black-Scholes	binomial	binomial
Risk free interest rate, minimum	0.27%	0.12%	0.12%
Risk free interest rate, maximum	1.81%	0.77%	1.78%
Risk free interest rate, weighted average	0.88%	0.35%	0.71%
Expected dividend yield, minimum	2.20%	1.70%	0.70%
Expected dividend yield, maximum	2.44%	1.90%	2.30%
Expected dividend yield, weighted average	2.34%	1.74%	1.31%
Expected life, minimum	2 years 4 months
Expected life, maximum	6 years 3 months	6 years 3 months	6 years 0 months 18 days
Expected life, weighted average	4 years 5 months 4 days
Expected volatility, minimum	28.64%	28.58%	33.42%
Expected volatility, maximum	44.35%	47.67%	50.12%
Expected volatility, weighted average	37.88%	39.72%	42.48%
Forfeiture rate, minimum		5.29%	7.55%
Forfeiture rate, maximum	7.00%	9.78%	13.41%
Forfeiture rate, weighted average		6.77%	9.48%
Employee stock options granted	760,322	733,297	770,245
Weighted average grant date fair value	$ 9.27	$ 10.08	$ 7.50
Equity Awards under 2006 Plan [Member]
Stock-Based Compensation (Details) [Line Items]
Number of shares authorized to issue	7,000,000
Stock Option Activity (Table Details) [Abstract]
Number of awards outstanding	1,729,969	1,616,983
Restricted Stock under 2006 Plan [Member]
Stock-Based Compensation (Details) [Line Items]
Number of shares authorized to issue	3,500,000
Equity Awards under Equity Incentive Plan [Member]
Stock-Based Compensation (Details) [Line Items]
Number of shares authorized to issue	2,468,461
Stock Option Activity (Table Details) [Abstract]
Number of awards outstanding	1,020,361	870,643
Equity Awards under Prior Plan [Member]
Stock-Based Compensation (Details) [Line Items]
Number of shares authorized to issue	14,562,865
Stock Option Activity (Table Details) [Abstract]
Number of awards outstanding	97,499	212,969
Stock Options [Member]
Stock-Based Compensation (Details) [Line Items]
Unvested awards - to result in compensation expense	10,300,000
Weighted average number of years to vesting	2 years 7 months 16 days
Restricted Stock Units (RSUs) [Member]
Stock-Based Compensation (Details) [Line Items]
Unvested awards - to result in compensation expense	$ 5,200,000
Weighted average number of years to vesting	1 year 10 months
Minimum [Member]
Stock-Based Compensation (Details) [Line Items]
Vesting period of options granted	1 year
Maximum [Member]
Stock-Based Compensation (Details) [Line Items]
Vesting period of options granted	4 years