Accounting for Share-Based Compensation 8 (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Employee Stock Purchase Plan [Member]	Jun. 30, 2012 Employee Stock Purchase Plan [Member]
Accounting for Share-Based Compensation (Textual) [Abstract]
Percentage of closing price of stock on last day of offer period			95.00%
Number of shares issued under Employee Stock Purchase Plan				0.1
Average price of shares issued under Employee Stock Purchase Plan				$ 25.74
Number of shares available for further issuances under Employee Stock Purchase Plan			29.9	29.9
Stock options issued	0.7	0.6
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected term, simplified method	The Company's computation of expected life was determined based on the simplified method (the average of the vesting period and option term).
Vesting period of shares issued under Sales Retention Equity Programs	3 years