Reconciliation of Company's Actual Tax Rate to U.S. Federal Statutory Rate (Detail)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income tax rates
- Statutory U.S. federal rate	21.00%	35.00%	35.00%
- State income taxes, net of federal benefit	0.00%	4.00%	3.00%
- Excess tax benefits related to stock compensation	0.00%	(20.00%)	0.00%
- Effect of 2017 Tax Act	2.00%	(12.00%)	0.00%
- Effect of 2018 net deferred tax asset valuation	(20.00%)	0.00%	0.00%
Total	3.00%	7.00%	38.00%

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 changes in the valuation allowance for deferred tax assets.

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