Income Taxes (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective tax rate (as a percent)	23.50%	38.10%
Unrecognized tax benefits increase			$ 0
Unrecognized tax benefits decrease			$ 0

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.4-08.(h)(2))
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Amount of decrease in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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