SHAREHOLDERS' EQUITY - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)		$ 7		$ (17)
Income tax (expense) or benefit		(154)		(314)
Net of tax		$ 566		$ 928
Blended statutory income tax rate		21.40%		25.30%
Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax		$ (12)		$ 10
Reclassification Out Of Accumulated Other Comprehensive Income | Unrealized gains (losses) on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)		(7)		17
Income tax (expense) or benefit		1	[1]	(4)	[2]
Net of tax		(6)		13
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)	[3]	(8)		(4)
Acquisition and operating expenses, prior service (cost) credit	[3]	0		0
Income tax (expense) or benefit		2	[1]	1	[2]
Net of tax		$ (6)		$ (3)

[1] Based on 21% blended tax rate

[2] Based on 25% blended tax rate

[3] These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details).