Stock Compensation Plans (Details) (Textual) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 13.57
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	8,000,000
Number Of Shares That Count Towards Shares Authorized Limit	1.61
Unearned compensation cost related to the unvested portion of all stock-based awards	$ 25
Grants Made in 2010 and 2011 [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Units Earned Of Units Granted	0.00%
Grants Made in 2010 and 2011 [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Units Earned Of Units Granted	150.00%
Grants Made in 2010 and after [Member] | Performance Plan 2008 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of Grants Payable In Shares of Common Stock	100.00%
Grants Made in 2012 and after [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Units Earned Of Units Granted	0.00%
Grants Made in 2012 and after [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Units Earned Of Units Granted	200.00%