Derivative Financial Instruments (Details 3) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Impact of Derivatives on Consolidated Statements of Changes in Stockholders' Equity (net of tax)
Total losses on cash flow hedges	$ (3)	$ (11)	$ (5)	$ (26)
Realized losses reclassified to interest expense	8	10	18	22
Hedge ineffectiveness reclassified to earnings		(1)	1
Total change in stockholders' equity for unrealized gains (losses) on derivatives	5	(2)	14	(4)
Collateral held:
Cash (obligation to return cash collateral is recorded in short-term borrowings)	1,003		1,003		886
Securities At Fair Value (not recorded in financial statements)	1,053		1,053		585
Total collateral held	2,056		2,056		1,471
Derivative asset at fair value including accrued interest	3,465		3,465		2,540
Collateral pledged to others:
Cash (right to receive return of cash collateral is recorded in investments)	993		993		809
Securities at fair value (recorded in restricted investments)	13		13		36
Total collateral pledged	1,006		1,006		845
Derivative liability at fair value including accrued interest and premium receivable	933		933		747
Derivative Financial Instruments (Textuals) [Abstract]
Net adjustments decreased the overall net asset position due to fair value adjustment	77		77		72
Fair value reflect adjustments for illiquid derivatives decreased the overall net asset position	112		112		129
Amount of after-tax net losses to be reclassified from accumulated other comprehensive income to earnings in the next 12 months			7
Collateral held in Restricted Cash	136		136		108
Derivative liability at fair value including accrued interest, net of premium receivable	864		864
Liability position with derivative counterparties	215		215
Collateral Already Posted, Aggregate Fair Value	$ 239		$ 239