Loans Receivable - Overall Statistics for Loans Receivable Portfolio (Parenthetical) (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Floating rate loans	$ 277.3	$ 147.9
Average floor rate	1.13%	1.80%
Percentage of loans subject to yield maintenance, or other prepayment restrictions	66.00%	64.00%
Percentage of loans open to repayment by borrower without penalty	34.00%	36.00%
USD LIBOR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of loans receivable by type	85.00%	84.00%