Employee Benefit Plans (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Stock Options	Jun. 30, 2014 Stock Options	Jun. 30, 2013 Stock Options	Jun. 30, 2014 Restricted Stock Units	Jun. 30, 2014 Restricted Stock Units	Jun. 30, 2014 Performance Stock Units	Dec. 31, 2013 Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Awards, Cumulative Shares Issued	7,100,000		7,100,000
Share-based awards available for grant	1,400,000		1,400,000
Share-based compensation expense	$ 5,500,000	$ 3,400,000	$ 8,700,000	$ 5,200,000
Unamortized compensation costs					19,800,000	19,800,000		17,200,000	17,200,000
Unamortized compensation costs, period for recognition					2 years			2 years
Proceeds from Stock Options Exercised	$ 4,100,000	$ 2,300,000	$ 4,060,000	$ 2,288,000
Weighted-average grant date fair value						$ 9.08	$ 9.94
Options Outstanding [Roll Forward]
Options outstanding at January 1, 2014						5,509,246
Options outstanding at January 1, 2014, weighted average exercise price, beginning balance						$ 14.01
Options granted, shares						711,380
Options granted, weighted average exercise price						$ 23.47
Options exercised, shares						(302,078)
Options exercised, weighted average exercise price						$ 13.03
Options cancelled or forfeited, shares						(218,950)
Options cancelled or forfeited, weighted average exercise price						$ 18.07
Options outstanding at June 30, 2014					5,699,598	5,699,598
Options outstanding, weighted average exercise price, ending balance					$ 15.11	$ 15.11
Options exercisable at June 30, 2014, shares					3,016,460	3,016,460
Options exercisable at June 30, 2014, weighted average exercise price					$ 12.46	$ 12.46
Expected to vest after June 30, 2014					2,041,655	2,041,655
Expected to Vest, Weighted Average Exercise Price					$ 18.43	$ 18.43
Unvested Shares [Roll Forward]
Unvested shares at January 1, 2014									629,518		431,858
Unvested shares at January 1, 2014, Weighted-average grant date fair value									$ 20.11		$ 0
Unvested shares granted									424,678	123,283
Unvested shares ganted, Weighted-average grant date fair value									$ 23.60	$ 26.50
Unvested shares vested									(120,638)
Unvested shares vested, Weighted-average grant date fair value									$ 18.65
Unvested shares cancelled/forfeited									(62,190)	0
Unvested shares cancelled/forfeited, Weighted-average grant date fair value									$ 21.93	$ 0.00
Unvested shares at June 30, 2014								871,368	871,368	555,141	431,858
Unvested shares at June 30, 2014, Weighted-average grant date fair value								$ 22.08	$ 22.08	$ 23.61	$ 0