Discontinued Operations - Additional Information (Detail) - USD ($)		3 Months Ended
	Jan. 09, 2015	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Discontinued Operations And Disposal Groups [Abstract]
Gross proceeds from sale of wholly owned subsidiary	$ 77,900,000
Payment for final working capital adjustment from buyer	$ 100,000
Proceeds released from escrow		$ 3,900,000	$ 74,100,000
Repurchase claims received or settled		0		$ 0
Repurchase reserve		700,000		$ 700,000
Decrease in allowance for repurchase reserve		$ 0	200,000
Pretax gain on sale of NABCO			$ 39,700,000