Loan Receivable - Summary of Loan Receivable (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Jacksonville, Florida [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ceiling rate, percentage	8.00%
Whole Loan [Member] | Jacksonville, Florida [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
LIBOR floor, percentage	6.00%
Mortgage Loans Payable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
LIBOR rate	1.56425%	0.77167%