Fair Value Measurements - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, measurements, nonrecurring - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Impaired loans measured at fair value on a nonrecurring basis
Individually evaluated loans, net of allowance for credit losses	$ 8,810	$ 24,145
OREO	215	2,736
Mortgage servicing rights	80,263	62,994
Total financial assets	89,288	89,875
Level 1
Impaired loans measured at fair value on a nonrecurring basis
Individually evaluated loans, net of allowance for credit losses	0	0
OREO	0	0
Mortgage servicing rights	0	0
Total financial assets	0	0
Level 2
Impaired loans measured at fair value on a nonrecurring basis
Individually evaluated loans, net of allowance for credit losses	0	0
OREO	0	0
Mortgage servicing rights	0	0
Total financial assets	0	0
Level 3
Impaired loans measured at fair value on a nonrecurring basis
Individually evaluated loans, net of allowance for credit losses	8,810	24,145
OREO	215	2,736
Mortgage servicing rights	80,263	62,994
Total financial assets	$ 89,288	$ 89,875