Income Taxes - Reconciliation of Statutory Federal Income Tax Rate to Our Effective Rate for Continuing Operations (Detail)	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	21.00%	21.00%	21.00%	21.00%
State income taxes, net of federal income tax	4.40%	5.10%	4.40%	5.10%
Stock compensation windfall benefit	(0.40%)	(0.10%)	(0.30%)	(4.20%)
Permanent differences and other	(2.20%)	(0.90%)	(1.90%)	(0.90%)
Total effective rate for continuing operations	22.80%	25.10%	23.20%	21.00%

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

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

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Percentage 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 other adjustments.

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Percentage of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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