GUARANTEES AND COMMITMENTS - Credit Commitments and Lines of Credit (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Credit Commitments
Credit commitments	$ 889,168,000,000	$ 904,040,000,000
Commercial and similar letters of credit
Credit Commitments
Credit commitments	5,715,000,000	6,634,000,000
One-to four-family residential mortgages
Credit Commitments
Credit commitments	4,116,000,000	5,674,000,000
Revolving open-end loans secured by one-to four-family residential properties
Credit Commitments
Credit commitments	15,956,000,000	16,098,000,000
Commercial real estate, construction and land development
Credit Commitments
Credit commitments	7,989,000,000	9,242,000,000
Credit card lines
Credit Commitments
Credit commitments	609,482,000,000	612,049,000,000
Commercial and other consumer loan commitments
Credit Commitments
Credit commitments	236,416,000,000	243,680,000,000
Commercial and other consumer loan commitments original maturity of less than 1 year	50,000,000,000	53,000,000,000
Other commitments and contingencies
Credit Commitments
Credit commitments	9,494,000,000	10,663,000,000
U.S.
Credit Commitments
Credit commitments	672,237,000,000
U.S. | Commercial and similar letters of credit
Credit Commitments
Credit commitments	1,037,000,000
U.S. | One-to four-family residential mortgages
Credit Commitments
Credit commitments	1,840,000,000
U.S. | Revolving open-end loans secured by one-to four-family residential properties
Credit Commitments
Credit commitments	13,597,000,000
U.S. | Commercial real estate, construction and land development
Credit Commitments
Credit commitments	6,817,000,000
U.S. | Credit card lines
Credit Commitments
Credit commitments	492,021,000,000
U.S. | Commercial and other consumer loan commitments
Credit Commitments
Credit commitments	152,069,000,000
U.S. | Other commitments and contingencies
Credit Commitments
Credit commitments	4,856,000,000
Outside U.S.
Credit Commitments
Credit commitments	216,931,000,000
Outside U.S. | Commercial and similar letters of credit
Credit Commitments
Credit commitments	4,678,000,000
Outside U.S. | One-to four-family residential mortgages
Credit Commitments
Credit commitments	2,276,000,000
Outside U.S. | Revolving open-end loans secured by one-to four-family residential properties
Credit Commitments
Credit commitments	2,359,000,000
Outside U.S. | Commercial real estate, construction and land development
Credit Commitments
Credit commitments	1,172,000,000
Outside U.S. | Credit card lines
Credit Commitments
Credit commitments	117,461,000,000
Outside U.S. | Commercial and other consumer loan commitments
Credit Commitments
Credit commitments	84,347,000,000
Outside U.S. | Other commitments and contingencies
Credit Commitments
Credit commitments	$ 4,638,000,000