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Income Taxes - Narrative (Details) - USD ($) $ in Millions |  | 12 Months Ended |
--- | --- | --- | ---
Jan. 18, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Income Taxes Disclosure [Line Items] |  |  |  |  |
Effective Income Tax Rate Reconciliation, Increase (Decrease) in Rate, Percent |  | 9.00% |  |  |
Effective income tax rate |  | 20.00% | 11.00% | 41.00% |
Effect of revaluation of deferred taxes |  | 0.10% | (20.00%) | (1.00%) |
Excess tax benefits |  | $ (48) | $ (47) | $ (1) |
Valuation allowance related to tax credit carryforwards |  | 6 | 6 |  |
Employment tax credit disallowed |  | 4 | 3 | 1 |
Unrecognized tax benefits |  | 6 | 6 | $ 1 | $ 3
Equity Incentive Plan Activities |  |  |  |  |
Income Taxes Disclosure [Line Items] |  |  |  |  |
Excess tax benefits |  | 10 |  |  |
State and Local Jurisdiction |  |  |  |  |
Income Taxes Disclosure [Line Items] |  |  |  |  |
Net operating loss carryforwards |  | 61 |  |  |
State tax credit carryforwards |  | 7 |  |  |
Uncertain Tax Positions |  |  |  |  |
Income Taxes Disclosure [Line Items] |  |  |  |  |
Unrecognized tax benefits |  | 6 | $ 6 |  |
Internal Revenue Service |  |  |  |  |
Income Taxes Disclosure [Line Items] |  |  |  |  |
Employment tax credit disallowed |  | 11 |  |  |
Income tax examination, penalties and interest expense |  | $ 4 |  |  |
Subsequent Event | Internal Revenue Service |  |  |  |  |
Income Taxes Disclosure [Line Items] |  |  |  |  |
Recovery of disallowed tax credits | $ 15 |  |  |  |

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- Definition Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.7) -URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319 + Details
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