Notes Receivable - Loans Receivable on Real Estate (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Receivables [Abstract]
Balance at January 1	$ 49,488	$ 41,988
Additions:
Interest	261	0
Accretion of discount	269	254
Deductions:
Collections of principal and interest	(134)	(126)
Balance at March 31	$ 49,884	$ 42,116