Fair Value of Financial Instruments - Equity Interest in Ernest and Related Loans Measured at Fair Value on Recurring Basis (Detail) $ in Thousands	Sep. 30, 2015 USD ($)
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	$ 219,167
Cost	219,167
Fair Value Measurements, Recurring [Member] | Equity investments [Member] | Other assets [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	3,300
Cost	3,300
Fair Value Measurements, Recurring [Member] | Acquisition loans [Member] | Other loans [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	114,367
Cost	114,367
Fair Value Measurements, Recurring [Member] | Other real estate loans [Member] | Other loans [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	1,500
Cost	1,500
Fair Value Measurements, Recurring [Member] | Mortgage loans [Member] | Mortgage loans [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	100,000
Cost	$ 100,000