Income Taxes, Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended					24 Months Ended
	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2018
Current:
Country	$ 573		$ 1,499		$ 488
U.S. state / Canadian provincial	103		95		47
Total current	676		1,594		535
Deferred:
Country	170		(2,551)		238
U.S. state / Canadian provincial	33		8		(8)
Total deferred	203		(2,543)		230
Income tax expense (benefit)	879		(949)		765
Deferred income tax expense (benefit) included in tax reform			(2,643)			$ (2,643)
U.S. [Member]
Current:
Country	432		1,305		294
U.S. state / Canadian provincial	37		34		12
Total current	469	[1]	1,339	[1]	306
Deferred:
Country	145		(2,522)		203
U.S. state / Canadian provincial	19		23		(4)
Total deferred	164	[2]	(2,499)	[2]	199
Income tax expense (benefit)	633		(1,160)		505
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	141		194		194
U.S. state / Canadian provincial	66		61		35
Total current	207		255		229
Deferred:
Country	25		(29)		35
U.S. state / Canadian provincial	14		(15)		(4)
Total deferred	39		(44)		31
Income tax expense (benefit)	$ 246		$ 211		$ 260

[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” above.

[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” above. Year Ended December 31, 2016 U.S. International TotalCurrent: Country$294 $194 $488U.S. state / Canadian provincial12 35 47Total current306 229 535Deferred: Country203 35 238U.S. state / Canadian provincial(4) (4) (8)Total deferred199 31 230Income tax expense$505 $260 $765