Activity in Allowance for Contract Cancellations (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance, beginning of period	$ 23,985
Balance, end of period	27,396
Contract Cancellations
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance, beginning of period	23,985	$ 22,138
Provision for cancellations	13,267	13,200
Charge-offs, net	(9,856)	(10,264)
Balance, end of period	$ 27,396	$ 25,074