Discontinued Operations - Additional Information (Detail) - USD ($)		3 Months Ended			6 Months Ended
	Jan. 09, 2015	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
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		$ 3,900,000	$ 74,100,000
Repurchase claims received or settled		$ 0			0		$ 0
Repurchase reserve		700,000			700,000		$ 700,000
Decrease in allowance for repurchase reserve		0		$ 200,000	0	4,800,000
Restitution received		$ 200,000		$ (300,000)	200,000	(500,000)
Pretax gain on sale of NABCO						39,700,000
Recovery of allowance for repurchase reserve						$ 4,800,000
Discontinued Operations
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Restitution received					$ 200,000