Mortgage Banking - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) CPR	Dec. 31, 2018 USD ($) CPR	Dec. 31, 2017 USD ($)
Schedule of changes in the reserve for mortgage loan [Abstract]
Assumed average prepayment speed | CPR	11	8
Average discount rate (in hundredths)	10.03%	10.04%
Annual servicing fee	$ 22,600	$ 21,900	$ 21,400
Servicing fee income percentage of outstanding balance of underlying loans (in hundredths)	0.32%
Mortgage servicing rights [Abstract]
Residential mortgage loans sold	$ 1,404,000	1,092,000	1,179,000
Gains on sales of residential mortgage loans	$ 30,300	21,800	$ 18,800
Period of putback response	60 days
Reserve for mortgage loan servicing putback expenses	$ 500	$ 1,000