Income Taxes, Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended					24 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2018
Current:
Country	$ 331	$ 573		$ 1,499
U.S. state / Canadian provincial	137	103		95
Total current	468	676		1,594
Deferred:
Country	262	170		(2,551)
U.S. state / Canadian provincial	(28)	33		8
Total deferred	234	203		(2,543)
Income tax expense	702	879		(949)
Deferred income tax expense (benefit) included in tax reform				(2,643)		$ (2,643)
U.S. [Member]
Current:
Country	145	432		1,305
U.S. state / Canadian provincial	37	37		34
Total current	182	469	[1]	1,339	[1]
Deferred:
Country	290	145		(2,522)
U.S. state / Canadian provincial	(16)	19		23
Total deferred	274	164	[2]	(2,499)	[2]
Income tax expense	456	633		(1,160)
Current income tax expense (benefit) included in tax reform adjustment		(21)		781
Deferred income tax expense (benefit) included in tax reform		9		(2,600)
International [Member]
Current:
Country	186	141		194
U.S. state / Canadian provincial	100	66		61
Total current	286	207		255
Deferred:
Country	(28)	25		(29)
U.S. state / Canadian provincial	(12)	14		(15)
Total deferred	(40)	39		(44)
Income tax expense	$ 246	$ 246		$ 211

[1] Current income tax expense includes a $21 million benefit and a $781 million expense related to our Tax Reform adjustment for the years ended December 31, 2018 and 2017, respectively, as described in “Tax Reform” below.

[2] Deferred income tax expense (benefit) includes a $9 million expense and a $2.6 billion benefit related to our Tax Reform adjustment for the years ended December 31, 2018 and 2017, respectively, as described in “Tax Reform” below.