Disclosures about Fair Value of Financial Instruments - Narrative (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Jun. 26, 2014	Sep. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, average life from purchase to sale (days)	22 days
Assets held for sale	$ 79,271,000	$ 2,680,000
Deposits held for sale, fair value	$ 456,795,000	247,068,000
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior unsecured notes aggregate amount			$ 25,000,000.0
Senior Notes Due 2018 | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior unsecured notes term (years)	5 years
Senior unsecured notes aggregate amount				$ 63,300,000.0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits held for sale, fair value	$ 456,795,000	247,068,000
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits held for sale, fair value	0	$ 0
Restricted Cash | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale, fair value	20,000,000
Loans Receivable | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale, fair value	$ 12,200,000