Employee Savings and Stock Ownership Plans (Details 2) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Employee Savings and Stock Ownership Plans
Dividends on shares held by the ESOP			$ 31
Company contributions to the ESOP			16
Interest incurred on ESOP notes			1
Amounts reported as employee benefit expense - expenses related to debt service			10
Amounts reported as employee benefit expense - expenses related to treasury shares			25
Amounts reported as employee benefit expense - expenses for Company contributions made in cash	$ 109	$ 97	$ 6
ESOP Debt Shares
Allocated (in shares)			14,473,474