Management Compensation Plans (Restricted Stock Units Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Performance-restricted and Time-Restricted Stock Units [Member] [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Holding period	seven years
Holding requirement range	0% to 75%
Time Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	29
Weighted-average term to recognize compensation expense	1.8
Management [Member] | Time Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	three to four years
Director [Member] | Time Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	one year