SHAREHOLDERS' EQUITY - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	$ 3,401	$ 5,432	$ 2,630	$ 625
Other comprehensive income loss before reclassifications net of tax	[1]	159	(90)	914	4,757
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	(29)	22	(13)	(18)
Other comprehensive income (loss), net of tax	[1]	130	(68)	901	4,739
Balance, end of period	[1]	3,531	5,364	3,531	5,364
Unrealized foreign currency translation gains (losses)
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	(1,580)	(847)	(1,983)	(2,196)
Other comprehensive income loss before reclassifications net of tax	[1]	(135)	253	268	1,602
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	0	0	0	0
Other comprehensive income (loss), net of tax	[1]	(135)	253	268	1,602
Balance, end of period	[1]	(1,715)	(594)	(1,715)	(594)
Unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	5,173	6,441	4,805	2,986
Other comprehensive income loss before reclassifications net of tax	[1]	296	(342)	653	3,155
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	(32)	21	(21)	(21)
Other comprehensive income (loss), net of tax	[1]	264	(321)	632	3,134
Balance, end of period	[1]	5,437	6,120	5,437	6,120
Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	(23)	(19)	(24)	(26)
Other comprehensive income loss before reclassifications net of tax	[1]	0	0	1	7
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	0	0	0	0
Other comprehensive income (loss), net of tax	[1]	0	0	1	7
Balance, end of period	[1]	(23)	(19)	(23)	(19)
Pension liability adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	(169)	(143)	(168)	(139)
Other comprehensive income loss before reclassifications net of tax	[1]	(2)	(1)	(8)	(7)
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	3	1	8	3
Other comprehensive income (loss), net of tax	[1]	1	0	0	(4)
Balance, end of period	[1]	$ (168)	$ (143)	$ (168)	$ (143)

[1] All amounts in the table above are net of tax.