Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions		1 Months Ended	3 Months Ended		10 Months Ended
	Apr. 01, 2018	May 09, 2018	Jun. 30, 2018	Mar. 31, 2018	May 09, 2018	Apr. 11, 2018	Jul. 13, 2017
Subsequent Event [Line Items]
Amount approved under share purchase program							$ 15,000,000
Class A common stock
Subsequent Event [Line Items]
Number of shares repurchased				0.5
Aggregate purchase price of repurchased shares				$ 2,400,000
Average price of repurchased shares				$ 4.78
Subsequent Event
Subsequent Event [Line Items]
Annualized savings on expense cuts	$ 8,000,000
Amount approved under share purchase program						$ 30,000,000
Subsequent Event | Class A common stock
Subsequent Event [Line Items]
Number of shares repurchased		1.0			2.5
Aggregate purchase price of repurchased shares		$ 5,100,000			$ 12,800,000
Average price of repurchased shares		$ 4.85			$ 5.10
Amount approved under share purchase program						$ 15,000,000
Scenario, Forecast
Subsequent Event [Line Items]
Severance costs			$ 800,000