Schedule of Aggregate Maturities of Long-Term Debt Obligations (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Contractually obligated payments for long-term debt due in 2013	$ 1,277
Contractually obligated payments for long-term debt due in 2014	38
Contractually obligated payments for long-term debt due in 2015	560
Contractually obligated payments for long-term debt due in 2016	1,259
Contractually obligated payments for long-term debt due in 2017	669
Contractually obligated payments for long-term debt due after 2018	3,282
Long-term debt	7,085	[1]	9,682	[1]
Parent Company [Member]
Debt Instrument [Line Items]
Contractually obligated payments for long-term debt due in 2013	758
Contractually obligated payments for long-term debt due in 2016	1,249
Contractually obligated payments for long-term debt due in 2017	583
Contractually obligated payments for long-term debt due after 2018	3,161
Total	5,751
Long-term debt	5,751		6,784
Subsidiaries [Member]
Debt Instrument [Line Items]
Contractually obligated payments for long-term debt due in 2013	519
Contractually obligated payments for long-term debt due in 2014	38
Contractually obligated payments for long-term debt due in 2015	560
Contractually obligated payments for long-term debt due in 2016	10
Contractually obligated payments for long-term debt due in 2017	86
Contractually obligated payments for long-term debt due after 2018	121
Total	$ 1,334

[1] At December 31, 2012 and 2011, includes $0 and $30 of cash, $0 and $7 of other short-term investments, $50 and $50 of commercial mortgage loans, $0 and $223 of home equity loans, $0 and $259 of automobile loans, ($5) and ($10) of ALLL, $3 and $4 of other assets, $0 and $4 of other liabilities, $0 and $191 of long-term debt from consolidated VIEs that are included in their respective captions. See Note 10.