SHAREHOLDERS' EQUITY - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	$ 6,807	$ 4,188	$ 8,934	$ 6,615
Other comprehensive income (loss) before reclassifications net of tax	1,208	2,501	(944)	(835)
Amounts reclassified from accumulated other comprehensive income net of tax	4	61	29	122
Other comprehensive income (loss), net of tax	1,212	2,562	(915)	(713)
Balance, end of period	8,019	6,750	8,019	6,750
Unrealized foreign currency translation gains (losses)
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(1,674)	(1,543)	(1,109)	(1,623)
Other comprehensive income (loss) before reclassifications net of tax	13	74	(552)	154
Amounts reclassified from accumulated other comprehensive income net of tax	0	0	0	0
Other comprehensive income (loss), net of tax	13	74	(552)	154
Balance, end of period	(1,661)	(1,469)	(1,661)	(1,469)
Unrealized gains (losses) on fixed maturity securities
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	8,794	6,043	10,361	8,548
Other comprehensive income (loss) before reclassifications net of tax	1,202	2,433	(381)	(975)
Amounts reclassified from accumulated other comprehensive income net of tax	(4)	56	12	111
Other comprehensive income (loss), net of tax	1,198	2,489	(369)	(864)
Balance, end of period	9,992	8,532	9,992	8,532
Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(33)	(35)	(34)	(33)
Other comprehensive income (loss) before reclassifications net of tax	(1)	(1)	(1)	(3)
Amounts reclassified from accumulated other comprehensive income net of tax	1	0	2	0
Other comprehensive income (loss), net of tax	0	(1)	1	(3)
Balance, end of period	(33)	(36)	(33)	(36)
Pension liability adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(280)	(277)	(284)	(277)
Other comprehensive income (loss) before reclassifications net of tax	(6)	(5)	(10)	(11)
Amounts reclassified from accumulated other comprehensive income net of tax	7	5	15	11
Other comprehensive income (loss), net of tax	1	0	5	0
Balance, end of period	$ (279)	$ (277)	$ (279)	(277)
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)