Capital Actions - Additional Information (Detail) (USD $)	9 Months Ended	0 Months Ended		1 Months Ended				1 Months Ended
	Sep. 30, 2011	Jan. 25, 2011 Group 1 [Member]	Oct. 24, 2011 Group 2 [Member]	Feb. 04, 2011 Group 5 [Member]	Feb. 02, 2011 Retained Earnings	Sep. 30, 2011 Trust Preferred Securities [Member]	Jun. 30, 2011 Trust Preferred Securities [Member]	Feb. 02, 2011 Preferred stock Series F	Mar. 16, 2011 Preferred stock Series F	Dec. 31, 2010 Preferred stock Series F	Sep. 30, 2010 Preferred stock Series F
Common stock issued, value	$ 1,648,000,000	$ 1,700,000,000
Common stock issued, shares		121,428,572	12,142,857
Common stock, market price		$ 14.00	$ 14.00
Forward sale agreement				959,821
Preferred shares repurchased								136,320
Accretion from redemption, Series F					153,000,000
Repurchase of warrants									280
Capital surplus, shares of common stock to purchase									43,617,747	43,617,747	43,617,747
Capital surplus, initial exercise price									11.72	11.72	11.72
Debt Instrument Principal Amount Redeemed						$ 40,000,000	$ 452,000,000