Stock-Based Compensation Compensation Expense (Details) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	May 17, 2011 2011 Plan	Jun. 30, 2013 Stock Options	Jun. 30, 2013 Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized					1,500,000
Stock-based compensation, equity classified awards	$ 2,700,000	$ 2,800,000	$ 5,900,000	$ 6,600,000
Stock-based compensation, liability classified awards	(600,000)	(300,000)	(100,000)	400,000
Pre-tax compensation expense	2,100,000	2,500,000	5,800,000	7,000,000
Tax provision	(800,000)	(1,000,000)	(2,200,000)	(2,700,000)
Total stock-based compensation expense, net of tax	1,300,000	1,500,000	3,600,000	4,300,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized						6,700,000	11,100,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition (in years)						1 year 9 months 18 days	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, outstanding, beginning of period						958,246
Options, granted						81,328
Options, exercised						(104,804)
Options, forfeited						(3,323)
Options, outstanding, end of period						931,447
Options, vested and expected to vest						899,916
Options, exercisable						653,600
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price, beginning of period						$ 39.67
Weighted average exercise price, granted						$ 72.28
Weighted average exercise price, exercised						$ 31.95
Weighted average exercise price, forfeited						$ 54.07
Weighted average exercise price, end of period						$ 43.34
Weighted average exercise price, vested and expected to vest						$ 42.74
Weighted average exercise price, exercisable						$ 37.91
Weighted average remaining contractual term (in years)						6 years 7 months 2 days
Weighted average remaining contractual term, vested and expected to vest (in years)						6 years 6 months 4 days
Weighted average remaining contractual term, exercisable (in years)						5 years 9 months
Options, outstanding, intrinsic value						24,061,000
Options, vested and expected to vest, intrinsic value						23,743,000
Options, vested and expected to vest, exercisable						$ 20,234,000