Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Tax Cuts and Jobs Act incomplete accounting transition tax unrepatriated earnings foreign subsidiaries payable period					8 years
U.S. federal statutory tax rate			21.00%		35.00%
Effective income tax rate	27.00%	34.00%	27.00%	32.00%
Unrecognized tax benefits	$ 0		$ 0
Unrecognized tax benefits recorded during period			$ 0

Tax Cuts and Jobs Act incomplete accounting transition tax unrepatriated earnings foreign subsidiaries payable period.

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- Definition

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

+ References

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- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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- Definition

Amount of unrecognized tax benefits.

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- Definition

Amount of increase (decrease) in unrecognized tax benefits attributable to uncertain tax positions taken in tax returns.

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