SHAREHOLDERS' EQUITY - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	$ 8,019	$ 6,750	$ 8,934	$ 6,615
Other comprehensive income (loss) before reclassifications net of tax	(355)	1,170	(1,298)	333
Amounts reclassified from accumulated other comprehensive income net of tax	(2)	(3)	26	121
Other comprehensive income (loss), net of tax	(357)	1,167	(1,272)	454
Balance, end of period	7,662	7,917	7,662	7,917
Unrealized foreign currency translation gains (losses)
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(1,661)	(1,469)	(1,109)	(1,623)
Other comprehensive income (loss) before reclassifications net of tax	(99)	179	(651)	333
Amounts reclassified from accumulated other comprehensive income net of tax	0	0	0	0
Other comprehensive income (loss), net of tax	(99)	179	(651)	333
Balance, end of period	(1,760)	(1,290)	(1,760)	(1,290)
Unrealized gains (losses) on fixed maturity securities
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	9,992	8,532	10,361	8,548
Other comprehensive income (loss) before reclassifications net of tax	(251)	995	(632)	20
Amounts reclassified from accumulated other comprehensive income net of tax	(10)	(7)	2	104
Other comprehensive income (loss), net of tax	(261)	988	(630)	124
Balance, end of period	9,731	9,520	9,731	9,520
Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(33)	(36)	(34)	(33)
Other comprehensive income (loss) before reclassifications net of tax	0	1	0	(2)
Amounts reclassified from accumulated other comprehensive income net of tax	2	0	3	0
Other comprehensive income (loss), net of tax	2	1	3	(2)
Balance, end of period	(31)	(35)	(31)	(35)
Pension liability adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(279)	(277)	(284)	(277)
Other comprehensive income (loss) before reclassifications net of tax	(5)	(5)	(15)	(18)
Amounts reclassified from accumulated other comprehensive income net of tax	6	4	21	17
Other comprehensive income (loss), net of tax	1	(1)	6	(1)
Balance, end of period	$ (278)	$ (278)	$ (278)	(278)
Cumulative effect, period of adoption, adjustment | Accounting Standards Update 2019-04
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				848
Cumulative effect, period of adoption, adjustment | Unrealized foreign currency translation gains (losses) | Accounting Standards Update 2019-04
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				0
Cumulative effect, period of adoption, adjustment | Unrealized gains (losses) on fixed maturity securities | Accounting Standards Update 2019-04
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				848
Cumulative effect, period of adoption, adjustment | Unrealized gains (losses) on derivatives | Accounting Standards Update 2019-04
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				0
Cumulative effect, period of adoption, adjustment | Pension liability adjustment | Accounting Standards Update 2019-04
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				0
Cumulative effect, period of adoption, adjusted balance
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				7,463
Cumulative effect, period of adoption, adjusted balance | Unrealized foreign currency translation gains (losses)
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				(1,623)
Cumulative effect, period of adoption, adjusted balance | Unrealized gains (losses) on fixed maturity securities
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				9,396
Cumulative effect, period of adoption, adjusted balance | Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				(33)
Cumulative effect, period of adoption, adjusted balance | Pension liability adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period				$ (277)