Employee Benefit Plans (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Awards, Cumulative Shares Issued	6,600,000
Share-based awards available for grant	2,400,000
Share-based compensation expense	$ 3,200,000	$ 1,800,000
Proceeds from Stock Options Exercised	2,277,000	962,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized compensation costs	17,500,000
Unamortized compensation costs, period for recognition	2 years
Weighted-average grant date fair value	$ 9.68	$ 7.82
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	128,700
Options granted, weighted average exercise price	$ 23.08
Options exercised, shares	(161,022)
Options exercised, weighted average exercise price	$ 13.44
Options cancelled or forfeited, shares	(118,200)
Options cancelled or forfeited, weighted average exercise price	$ 18.01
Options outstanding at March 31, 2014	5,358,724
Options outstanding, weighted average exercise price, ending balance	$ 14.15
Options exercisable at March 31, 2014, shares	2,748,717
Options exercisable at March 31, 2014, weighted average exercise price	$ 12.34
Expected to vest after March 31, 2014	1,989,323
Expected to Vest, Weighted Average Exercise Price	$ 16.32
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized compensation costs	$ 12,700,000
Unamortized compensation costs, period for recognition	2 years
Unvested Shares [Roll Forward]
Unvested shares at January 1, 2014	629,518
Unvested shares at January 1, 2014, Weighted-average grant date fair value	$ 20.11
Unvested shares granted	114,138
Unvested shares ganted, Weighted-average grant date fair value	$ 23.64
Unvested shares vested	(19,115)
Unvested shares vested, Weighted-average grant date fair value	$ 13.42
Unvested shares cancelled/forfeited	(34,585)
Unvested shares cancelled/forfeited, Weighted-average grant date fair value	$ 22.22
Unvested shares at March 31, 2014	689,956
Unvested shares at March 31, 2014, Weighted-average grant date fair value	$ 20.99
Performance Stock Units
Unvested Shares [Roll Forward]
Unvested shares at January 1, 2014	431,858
Unvested shares at January 1, 2014, Weighted-average grant date fair value	$ 0
Unvested shares granted	123,283
Unvested shares ganted, Weighted-average grant date fair value	$ 26.50
Unvested shares cancelled/forfeited	0
Unvested shares cancelled/forfeited, Weighted-average grant date fair value	$ 0.00
Unvested shares at March 31, 2014	555,141
Unvested shares at March 31, 2014, Weighted-average grant date fair value	$ 23.61