Equity (Other Comprehensive Income (Loss) Adjustments) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative [Line Items]
Unrealized (losses) gains, Net-of-tax	$ 127			$ (113)			$ (52)	$ (212)
Reclassifications, Net-of-tax	(4)			(3)			(24)	(2)
Other comprehensive income (loss)	123	$ 101	$ (300)	(116)	$ (18)	$ (80)	(76)	(214)
AOCI Including Portion Attributable to Noncontrolling Interest
Derivative [Line Items]
Other comprehensive (loss) income, Pretax	117			(102)			(145)	(211)
Other comprehensive (loss) income, Tax Benefit (Expense)	6			(14)			69	(3)
Other comprehensive income (loss)	123			(116)			(76)	(214)
Currency Translation
Derivative [Line Items]
Unrealized (losses) gains, Net-of-tax	101			(146)				(211)
Reclassifications, Net-of-tax	0			0			0	6
Other comprehensive (loss) income, Pretax	87			(141)			52	(199)
Other comprehensive (loss) income, Tax Benefit (Expense)	14			(5)			24	(6)
Other comprehensive income (loss)	101			(146)			76	(205)
Currency Translation | Foreign currency
Derivative [Line Items]
Unrealized (losses) gains, Pretax		$ 193		(242)			29	(333)
Unrealized (losses) gains, Tax Benefit (Expense)	(11)			(5)			46	(6)
Unrealized (losses) gains, Net-of-tax	182			(247)			75	(339)
Currency Translation | Foreign currency | Loss on disposition
Derivative [Line Items]
Reclassifications, Pretax							0	6
Reclassifications, Tax Benefit (Expense)							0	0
Reclassifications, Net-of-tax							0	6
Currency Translation | Net investment hedges
Derivative [Line Items]
Unrealized (losses) gains, Pretax	(106)			101			23	128
Unrealized (losses) gains, Tax Benefit (Expense)	25			0			(22)	0
Unrealized (losses) gains, Net-of-tax	(81)			101			1	128
Derivatives
Derivative [Line Items]
Unrealized (losses) gains, Pretax	35			41			(168)	(3)
Unrealized (losses) gains, Tax Benefit (Expense)	(9)			(8)			40	2
Unrealized (losses) gains, Net-of-tax	26			33			(128)	(1)
Reclassifications, Net-of-tax	(4)			(3)			(24)	(8)
Other comprehensive (loss) income, Pretax	30			39			(197)	(12)
Other comprehensive (loss) income, Tax Benefit (Expense)	(8)			(9)			45	3
Other comprehensive income (loss)	22			30			(152)	(9)
Derivatives | Income Statement Items
Derivative [Line Items]
Reclassifications, Pretax	(5)			(2)			(29)	(9)
Reclassifications, Tax Benefit (Expense)	1			(1)			5	1
Reclassifications, Net-of-tax	$ (4)			$ (3)			$ (24)	$ (8)