Share-Based Compensation Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	1 Months Ended			12 Months Ended						12 Months Ended
	Jul. 26, 2012	May 31, 2011	Sep. 30, 2010	Feb. 28, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 2012 Equity Incentive Award Plan [Member]	May 24, 2012 2012 Equity Incentive Award Plan [Member]	Dec. 31, 2012 All Company Incentive Stock Plans [Member]	Dec. 31, 2012 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Shares Authorized					5,000,000	5,000,000
Share Repurchase Program [Abstract]
Stock Repurchase Program, Authorized Amount	$ 90.0		$ 30.0	$ 15.0
Stock Repurchase Program, Additional Authorized Amount	30.0	30.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount					19.1
Stock Repurchased During Period, Shares					3,431,548
Stock Repurchased During Period, Value					$ 34.6
Incentive Award Plans [Abstract]
Number of shares reserved for issuance under the plan									6,000,000		2,000,000
Reduction in shares available for issuance under the current plan for shares issued under the prior plan								2
Number of shares available for grant								5,548,487
Number of shares reserved for future issuance										14,581,806
Employee Stock Purchase Plan [Abstract]
Discounted market value of stock, percent											95.00%
Stock issued during the period under the plan					38,497	32,386	30,688
Weighted average purchase price per share of shares purchased					$ 9.40	$ 10.21	$ 10.35