SHAREHOLDERS' EQUITY - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021		Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)		$ 20		$ 7
Income tax (expense) or benefit		(310)		(154)
Net of tax		$ 1,293		$ 566
U.S. federal statutory income tax rate		21.00%
Blended statutory income tax rate				21.00%
Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax		$ (24)		$ (12)
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)		(20)		(7)
Income tax (expense) or benefit		4	[1]	1	[2]
Net of tax		(16)		(6)
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]	(10)		(8)
Acquisition and operating expenses, prior service (cost) credit	[3]	0		0
Income tax (expense) or benefit		2	[1]	2	[2]
Net of tax		$ (8)		$ (6)

[1] Based on 21% tax rate

[2] Based on 21% blended tax rate

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