Stock Compensation Plans and Other Compensation Arrangements (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	6 Months Ended
	Feb. 15, 2012	Jun. 30, 2012
Restricted Stock Rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, cash units, or cash performance units granted	0.5
Vesting period of stock awards		3 years
Restricted Performance Stock Rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, cash units, or cash performance units granted	1.2
Vesting period of stock awards		3 years
Restricted Stock Rights and Restricted Performance Stock Rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested awards	102
Cash Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, cash units, or cash performance units granted	0.6
Vesting period of stock awards		3 years
Cash Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, cash units, or cash performance units granted	1.3
Vesting period of stock awards		3 years
Minimum | Cash Units and Cash Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested awards	34
Maximum | Cash Units and Cash Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested awards	190