INVESTMENT SECURITIES - Schedule of Investment Securities (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		$ 34,464		$ 34,464		$ 40,665
Gross unrealized gains		4,368		4,368		3,917
Gross unrealized losses		(136)		(136)		(269)
Estimated fair value		38,696		38,696		44,313
Investment securities		38,696		38,696		44,313
Trading securities included in estimated fair values		107		107		17
Net unrealized gains (losses) recorded to earnings related to trading securities		12	$ 1	41	$ (2)
U.S. corporate
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		20,255		20,255		20,049
Gross unrealized gains		3,594		3,594		3,081
Gross unrealized losses		(45)		(45)		(85)
Estimated fair value		23,804		23,804		23,046
Non-U.S. corporate
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		5,615		5,615		11,917
Gross unrealized gains		84		84		98
Gross unrealized losses		(13)		(13)		(27)
Estimated fair value		5,686		5,686		11,987
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		3,827		3,827		3,916
Gross unrealized gains		506		506		412
Gross unrealized losses		(49)		(49)		(92)
Estimated fair value		4,284		4,284		4,236
Mortgage and asset-backed
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		2,808		2,808		2,787
Gross unrealized gains		97		97		111
Gross unrealized losses		(19)		(19)		(37)
Estimated fair value		2,886		2,886		2,861
Government and agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		1,769		1,769		1,842
Gross unrealized gains		74		74		160
Gross unrealized losses		(10)		(10)		(26)
Estimated fair value		1,833		1,833		1,976
Equity
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		191		191		154
Gross unrealized gains		13		13		55
Gross unrealized losses		0		0		(1)
Estimated fair value		204		204		208
GE
Schedule of Available-for-sale Securities [Line Items]
Investment securities	[1]	384		384		137
Equity securities		$ 149		$ 149		$ 86

[1] Represents the adding together of all affiliated companies except GE Capital, which is presented on a one-line basis. See Note 1.