Income Taxes [Line Items]

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- Definition

Amount of income tax expense (benefit) for measurement period adjustment from accounting for tax effect pursuant to Tax Cuts and Jobs Act.

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- Definition

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

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

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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 increase (decrease) in the income tax rates.

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2018
Income Taxes [Line Items]
Income tax expense	$ 3,490,000	$ 4,220,000		$ 2,792,000	$ 4,132,000
Effective income tax rate				31.60%	31.20%
Income tax expense decreased due to decrease in federal tax rate due to Tax Cuts and Jobs Act				$ 1,300,000
Tax Cuts and Jobs Act, Measurement Period Adjustment, Income Tax Expense (Benefit)				$ 0
Settlement from Tax Audit [Member]
Income Taxes [Line Items]
Tax benefit recognized			$ 1,300,000
Anticipated [Member]
Income Taxes [Line Items]
Effective income tax rate						32.00%