Equity (Other Comprehensive Income (Loss) Adjustments) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative [Line Items]
Unrealized (losses) gains, Net-of-tax	$ 113		$ (22)		$ (179)	$ (99)
Reclassifications, Net-of-tax	(12)		4		(20)	1
Other comprehensive income (loss)	101	$ (300)	(18)	$ (80)	(199)	(98)
AOCI Including Portion Attributable to Noncontrolling Interest
Derivative [Line Items]
Other comprehensive (loss) income, Pretax	86		(23)		(262)	(109)
Other comprehensive (loss) income, Tax Benefit (Expense)	15		5		63	11
Other comprehensive income (loss)	101		(18)		(199)	(98)
Currency Translation
Derivative [Line Items]
Unrealized (losses) gains, Net-of-tax	116		4			(65)
Reclassifications, Net-of-tax	0		6		0	6
Other comprehensive (loss) income, Pretax	107		13		(35)	(58)
Other comprehensive (loss) income, Tax Benefit (Expense)	9		(3)		10	(1)
Other comprehensive income (loss)	116		10		(25)	(59)
Currency Translation | Foreign currency
Derivative [Line Items]
Unrealized (losses) gains, Pretax	145		7		(164)	(91)
Unrealized (losses) gains, Tax Benefit (Expense)	10		(3)		57	(1)
Unrealized (losses) gains, Net-of-tax	155		4		(107)	(92)
Currency Translation | Foreign currency | Loss on disposition
Derivative [Line Items]
Reclassifications, Pretax	0		(6)		0	6
Reclassifications, Tax Benefit (Expense)	0		0		0	0
Reclassifications, Net-of-tax	0		(6)		0	6
Currency Translation | Net investment hedges
Derivative [Line Items]
Unrealized (losses) gains, Pretax	(38)		0		129	27
Unrealized (losses) gains, Tax Benefit (Expense)	(1)		0		(47)	0
Unrealized (losses) gains, Net-of-tax	(39)		0		82	27
Derivatives
Derivative [Line Items]
Unrealized (losses) gains, Pretax	(7)		(32)		(203)	(44)
Unrealized (losses) gains, Tax Benefit (Expense)	4		6		49	10
Unrealized (losses) gains, Net-of-tax	(3)		(26)		(154)	(34)
Reclassifications, Net-of-tax	(12)		(2)		(20)	(5)
Other comprehensive (loss) income, Pretax	(21)		(36)		(227)	(51)
Other comprehensive (loss) income, Tax Benefit (Expense)	6		8		53	12
Other comprehensive income (loss)	(15)		(28)		(174)	(39)
Derivatives | Income Statement Items
Derivative [Line Items]
Reclassifications, Pretax	14		4		(24)	(7)
Reclassifications, Tax Benefit (Expense)	(2)		(2)		4	2
Reclassifications, Net-of-tax	$ 12		$ 2		$ (20)	$ (5)