INCOME TAXES - Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets
Credit loss deduction	$ 3,419	$ 3,423
Deferred compensation and employee benefits	1,975	1,585
Repositioning and settlement reserves	428	454
U.S. tax on non-U.S. earnings	2,080	2,452
Investment and loan basis differences	4,891	3,384
Cash flow hedges	240	233
Tax credit and net operating loss carry-forwards	20,759	21,575
Fixed assets and leases	1,006	1,090
Other deferred tax assets	2,145	1,988
Gross deferred tax assets	36,943	36,184
Valuation allowance	9,258	9,387
Deferred tax assets after valuation allowance	27,685	26,797
Deferred tax liabilities
Intangibles	(975)	(1,247)
Debt issuances	(530)	(294)
Non-U.S. withholding taxes	(1,040)	(668)
Interest-related items	(594)	(562)
Other deferred tax liabilities	(1,643)	(1,545)
Gross deferred tax liabilities	(4,782)	(4,316)
Net deferred tax assets	$ 22,903	$ 22,481