Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule Of Income Taxes [Line Items]
Federal and state income tax expense (benefit)	$ (2,500,000)	$ 100,000	$ (2,200,000)	$ 600,000
Unrecognized tax benefits	0	$ 0	0	0
Deferred tax liability	3,000,000		3,000,000
Interest or penalties related to uncertain tax positions			0	$ 0
Deferred tax assets	$ 5,100,000		$ 5,100,000
Tax Year 2013 [Member]
Schedule Of Income Taxes [Line Items]
Tax years open to examination			2013
Latest Tax Year [Member]
Schedule Of Income Taxes [Line Items]
Tax years open to examination			2016