Stock-Based Compensation Plans (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based, Compensation Cost	$ 1,300,000	$ 2,300,000	$ 4,800,000	$ 3,700,000
Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	8,600,000		8,600,000
Deferred Compensation, Share-based Payments [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation, Shares Outstanding	0.7	0.7
Deferred Compensation, Compensation Expense	(200,000)	400,000	500,000	300,000
Stock Options SARs and Restricted Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			2
Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			1
Contingent Compensation Data Center Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum payout of contingent compensation plan	90,000,000		90,000,000
Payout of contingent compensation plan threshold value	$ 1,000,000,000		$ 1,000,000,000