Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	May 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense (benefit)		$ 5,117	$ 4,763	$ 9,130	$ 11,885
Effective tax rate		44.40%	33.30%	34.70%	35.50%
Income taxes at statutory rate, percentage				21.00%		35.00%
Derecognition of deferred tax assets		$ 1,620		$ 1,620
Disallowance of the deductibility dividends paid	$ 1,727	$ 1,727