Income Taxes - Reconciliation of Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Federal statutory tax rate	35.00%	35.00%	35.00%
Reconciliation of Statutory to Effective Tax (Benefit) Expense
U.S. Federal income tax expense at the statutory rate of 35%	$ 307	$ 422	$ 213
Deferred tax impact of enacted tax rate and law changes	389	(2)	(2)
Provision for undistributed foreign earnings, net	(162)	0	0
Transition tax (repatriation)	77	0	0
Adjustment for foreign income taxed at different rates	(55)	(51)	(39)
U.S. credits (R&D, foreign tax credits) and benefits offset to OCI	(23)	(163)	(72)
Domestic production activities deduction	(16)	(3)	0
State income taxes, net of U.S. Federal benefit	9	16	10
Net foreign losses (income) with no tax due to valuation allowances	(7)	8	(19)
Net establishment (resolution) of uncertain tax positions	(6)	3	(13)
Deconsolidation of Venezuelan subsidiary	0	0	157
Other	(6)	8	1
United States and Foreign Tax (Benefit) Expense	513	(77)	232
Foreign Tax Authority
Reconciliation of Statutory to Effective Tax (Benefit) Expense
Net establishment (release) of valuation allowances	1	(354)	4
Domestic Tax Authority
Reconciliation of Statutory to Effective Tax (Benefit) Expense
Net establishment (release) of valuation allowances	$ 5	$ 39	$ (8)