Receivables - Receivables (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 18,561	$ 8,957
Allowance for bad debts	(26)	(26)
Receivables, net	18,535	8,931
Funds held by escrow agent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	7,689	0
Receivables and accrued interest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,466	1,505
Notes receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 9,406	$ 7,452
Average interest rates	4.85%	4.94%