SHAREHOLDERS' EQUITY - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales and redemptions		$ 5	$ 22	$ (1)	$ 113
Other than temporary impairment losses realized		(9)	(33)	(19)	(47)
Total before tax		1,045	834	1,944	1,951
Income tax (expense) or benefit		(332)	(286)	(639)	(672)
Net of tax		$ 713	$ 548	$ 1,305	$ 1,279
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		$ (4)	$ (8)	$ (16)	$ 42
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		5	22	(1)	113
Other than temporary impairment losses realized		(6)	(33)	(16)	(47)
Total before tax		(1)	(11)	(17)	66
Income tax (expense) or benefit	[1]	0	4	6	(23)
Net of tax		(1)	(7)	(11)	43
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]	(5)	(5)	(8)	(8)
Acquisition and operating expenses, prior service (cost) credit	[2]	0	3	0	6
Income tax (expense) or benefit	[1]	2	1	3	1
Net of tax		$ (3)	$ (1)	$ (5)	$ (1)

[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).