Discontinued Operations - Summary of Net Gain from Sale of Discontinued Operations (Detail) - USD ($)	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Discontinued Operations And Disposal Groups [Abstract]
Gain from sale of discontinued operations before income taxes	$ 862,000	$ 862,000
Less current income tax expense	198,000	198,000
Net gain from sale of discontinued operations	$ 664,000	$ 664,000

Amount after tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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