SHAREHOLDERS' EQUITY - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended								9 Months Ended
		Sep. 30, 2021		Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020		Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021		Sep. 30, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)		$ (13)				$ (13)				$ 2		$ 132
Income tax (expense) or benefit		(225)				1,303				(804)		884
Net of tax		$ 888		$ 1,105	$ 1,293	$ 2,456		$ 805	$ 566	$ 3,286		$ 3,826
U.S. federal statutory income tax rate		21.00%				21.00%				21.00%		21.00%
Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains (losses) on derivatives during period		$ (1)								$ (3)
Net of tax		2				$ 3				(26)		$ (121)
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)		13				13				(2)		(132)
Income tax (expense) or benefit		(3)	[1]			(6)	[2]			0	[1]	28	[1]
Net of tax		10				7				(2)		(104)
Reclassification Out Of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains (losses) on derivatives during period		(2)								(4)
Income tax (expense) or benefit	[1]	0								1
Net of tax		(2)								(3)
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)				(7)				(27)		(22)
Acquisition and operating expenses, prior service (cost) credit	[3]	0				0				0		0
Income tax (expense) or benefit		2	[1]			3	[2]			6	[1]	5	[1]
Net of tax		$ (6)				$ (4)				$ (21)		$ (17)

[1] Based on 21% tax rate

[2] Based on 21% tax rate, with a cumulative adjustment to the first six months of 2020 due to the effects of Final and Proposed Regulations released on September 29, 2020 by the U.S. Treasury and Internal Revenue Service and addressing, among other items, the allocation of insurance expenses in the calculation of the foreign tax credit limitation. See Note 10 of the Notes to the Consolidated Financial Statements in the Company's 2020 Annual Report on Form 10-K.

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