Mortgage Servicing Rights - Loans, Fees, Amortization and Carrying Value (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Other Intangible Assets
Unpaid principal amount of consumer loans serviced for others	$ 1,800,000		$ 1,800,000		$ 2,200,000
Contractually specified fees, late charges, and ancillary fees	1,100	$ 1,400	3,700	$ 4,400
Amortization of mortgage servicing rights	1,001	$ 1,402	2,830	$ 4,681
Details of MSRs
Gross carrying amount	69,062		69,062		67,856
Less: accumulated amortization	59,955		59,955		57,125
Net carrying value	9,107		9,107		$ 10,731
MSRs
Estimated future amortization expenses for MSRs over the next five years
Under one year	1,860		1,860
One to two years	1,434		1,434
Two to three years	1,142		1,142
Three to four years	926		926
Four to five years	$ 763		$ 763