Notes Receivable - Summary of Activity in Loan Loss Reserve (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Balance at January 1	$ 15,606	$ 15,106
Additions:
Loan loss reserve	0	500
Deductions:
Write-offs	(15,606)	0
Balance at December 31	$ 0	$ 15,606