Loan Servicing - Schedule of Loans Serviced Not Reported as Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Federal Home Loan Mortgage Corporation
Loans Servicing For Institutional Investors [Line Items]
Loans serviced for others	$ 488,790	$ 492,761
Federal National Mortgage Association
Loans Servicing For Institutional Investors [Line Items]
Loans serviced for others	10,221	0
Other
Loans Servicing For Institutional Investors [Line Items]
Loans serviced for others	$ 3,504	$ 3,689