GUARANTEES AND COMMITMENTS - Credit Commitments and Lines of Credit (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Credit Commitments
Credit commitments	$ 898,155	$ 904,040
Commercial and similar letters of credit
Credit Commitments
Credit commitments	6,359	6,634
One-to four-family residential mortgages
Credit Commitments
Credit commitments	3,868	5,674
Revolving open-end loans secured by one-to four-family residential properties
Credit Commitments
Credit commitments	15,664	16,098
Commercial real estate, construction and land development
Credit Commitments
Credit commitments	8,415	9,242
Credit card lines
Credit Commitments
Credit commitments	603,306	612,049
Commercial and other consumer loan commitments
Credit Commitments
Credit commitments	249,533	243,680
Commercial and other consumer loan commitments original maturity of less than 1 year	52,000	53,000
Other commitments and contingencies
Credit Commitments
Credit commitments	11,010	$ 10,663
U.S.
Credit Commitments
Credit commitments	677,592
U.S. | Commercial and similar letters of credit
Credit Commitments
Credit commitments	1,358
U.S. | One-to four-family residential mortgages
Credit Commitments
Credit commitments	1,669
U.S. | Revolving open-end loans secured by one-to four-family residential properties
Credit Commitments
Credit commitments	13,303
U.S. | Commercial real estate, construction and land development
Credit Commitments
Credit commitments	6,938
U.S. | Credit card lines
Credit Commitments
Credit commitments	486,115
U.S. | Commercial and other consumer loan commitments
Credit Commitments
Credit commitments	163,579
U.S. | Other commitments and contingencies
Credit Commitments
Credit commitments	4,630
Outside U.S.
Credit Commitments
Credit commitments	220,563
Outside U.S. | Commercial and similar letters of credit
Credit Commitments
Credit commitments	5,001
Outside U.S. | One-to four-family residential mortgages
Credit Commitments
Credit commitments	2,199
Outside U.S. | Revolving open-end loans secured by one-to four-family residential properties
Credit Commitments
Credit commitments	2,361
Outside U.S. | Commercial real estate, construction and land development
Credit Commitments
Credit commitments	1,477
Outside U.S. | Credit card lines
Credit Commitments
Credit commitments	117,191
Outside U.S. | Commercial and other consumer loan commitments
Credit Commitments
Credit commitments	85,954
Outside U.S. | Other commitments and contingencies
Credit Commitments
Credit commitments	$ 6,380