Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Federal, state and withholding taxes related to partial indefinite reversal assertion	$ 2
Deferred tax assets, valuation allowance	73	$ 93
Decrease in valuation allowance	20
Reduction to unrecognized tax benefits	4
Internal Revenue Service (IRS)
Income Tax Contingency [Line Items]
Operating loss carryforwards	82	188
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Operating loss carryforwards	26	33
Tax credit carryforwards	8	10
Domestic Tax Authority
Income Tax Contingency [Line Items]
Tax credit carryforwards	16	34
Deferred tax assets, valuation allowance	73
Foreign Tax Authority
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 382	$ 332