SHAREHOLDERS' EQUITY - Reclassifications Out of 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
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales and redemptions		$ 61	$ (14)	$ 60	$ 100
Other than temporary impairment losses realized		(8)	(23)	(27)	(71)
Total before tax		1,075	963	3,019	2,914
Income tax (expense) or benefit		(359)	(334)	(998)	(1,006)
Net of tax		$ 716	$ 629	$ 2,021	$ 1,908
The expected U.S. tax rate		35.00%	35.00%	35.00%	35.00%
Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax		$ 29	$ (22)	$ 13	$ 18
Reclassification Out Of Accumulated Other Comprehensive Income | Unrealized gains (losses) on investment securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales and redemptions		56	(11)	56	102
Other than temporary impairment losses realized		(6)	(22)	(23)	(69)
Total before tax		50	(33)	33	33
Income tax (expense) or benefit	[1]	(18)	12	(12)	(12)
Net of tax		32	(21)	21	21
Reclassification Out Of Accumulated Other Comprehensive Income | Pension liability adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Acquisition and operating expenses, actuarial gains (losses)	[2]	(4)	(4)	(12)	(12)
Acquisition and operating expenses, prior service (cost) credit	[2]	0	2	0	8
Income tax (expense) or benefit	[1]	1	1	4	1
Net of tax		$ (3)	$ (1)	$ (8)	$ (3)

[1] Based on 35% tax rate

[2] These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 11 for additional details).