Allowance for Loan Losses - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019
Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Actual loss history experienced by the Company	1 year
Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Actual loss history experienced by the Company	5 years
Allowance for loan losses charge down family first and junior lien mortgages past due period	180 days
Allowance for loan losses charge down unsecured open end loans past due period	90 days
Allowance for loan losses charge down other secured loans past due period	90 days