SHAREHOLDERS' EQUITY - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	$ 6,615	$ 2,151	$ 4,028
Other comprehensive income loss before reclassifications net of tax	1,322	4,466	(2,150)
Amounts reclassified from accumulated other comprehensive income net of tax	149	(2)	47
Other comprehensive income (loss), net of tax	1,471	4,464	(2,103)
Balance, end of period	8,934	6,615	2,151
Cumulative effect, period of adoption, adjusted balance
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	7,463		4,254
Balance, end of period		7,463
Accounting Standards Update 2019-04 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	848
Balance, end of period		848
Accounting Standards Update 2016-01 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			(148)
Accounting Standards Update 2018-02 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			374
Unrealized foreign currency translation gains (losses)
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(1,623)	(1,847)	(1,750)
Other comprehensive income loss before reclassifications net of tax	514	224	228
Amounts reclassified from accumulated other comprehensive income net of tax	0	0	0
Other comprehensive income (loss), net of tax	514	224	228
Balance, end of period	(1,109)	(1,623)	(1,847)
Unrealized foreign currency translation gains (losses) | Cumulative effect, period of adoption, adjusted balance
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(1,623)		(2,075)
Balance, end of period		(1,623)
Unrealized foreign currency translation gains (losses) | Accounting Standards Update 2019-04 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	0
Balance, end of period		0
Unrealized foreign currency translation gains (losses) | Accounting Standards Update 2016-01 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			0
Unrealized foreign currency translation gains (losses) | Accounting Standards Update 2018-02 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			(325)
Unrealized gains (losses) on available-for-sale securities
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	8,548	4,234	5,964
Other comprehensive income loss before reclassifications net of tax	839	4,327	(2,350)
Amounts reclassified from accumulated other comprehensive income net of tax	126	(13)	34
Other comprehensive income (loss), net of tax	965	4,314	(2,316)
Balance, end of period	10,361	8,548	4,234
Unrealized gains (losses) on available-for-sale securities | Cumulative effect, period of adoption, adjusted balance
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	9,396		6,550
Balance, end of period		9,396
Unrealized gains (losses) on available-for-sale securities | Accounting Standards Update 2019-04 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	848
Balance, end of period		848
Unrealized gains (losses) on available-for-sale securities | Accounting Standards Update 2016-01 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			(148)
Unrealized gains (losses) on available-for-sale securities | Accounting Standards Update 2018-02 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			734
Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(33)	(24)	(23)
Other comprehensive income loss before reclassifications net of tax	(1)	(9)	2
Amounts reclassified from accumulated other comprehensive income net of tax	0	0	0
Other comprehensive income (loss), net of tax	(1)	(9)	2
Balance, end of period	(34)	(33)	(24)
Unrealized gains (losses) on derivatives | Cumulative effect, period of adoption, adjusted balance
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(33)		(26)
Balance, end of period		(33)
Unrealized gains (losses) on derivatives | Accounting Standards Update 2019-04 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	0
Balance, end of period		0
Unrealized gains (losses) on derivatives | Accounting Standards Update 2016-01 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			0
Unrealized gains (losses) on derivatives | Accounting Standards Update 2018-02 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			(3)
Pension liability adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(277)	(212)	(163)
Other comprehensive income loss before reclassifications net of tax	(30)	(76)	(30)
Amounts reclassified from accumulated other comprehensive income net of tax	23	11	13
Other comprehensive income (loss), net of tax	(7)	(65)	(17)
Balance, end of period	(284)	(277)	(212)
Pension liability adjustment | Cumulative effect, period of adoption, adjusted balance
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	(277)		(195)
Balance, end of period		(277)
Pension liability adjustment | Accounting Standards Update 2019-04 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	$ 0
Balance, end of period		$ 0
Pension liability adjustment | Accounting Standards Update 2016-01 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			0
Pension liability adjustment | Accounting Standards Update 2018-02 | Cumulative effect, period of adoption, adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period			$ (32)