Fair Value Measurements - Fair Value of Assets Measured on Nonrecurring Basis (Details) - Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans, net of allowance for credit losses	$ 24,145	$ 27,348
OREO	2,736	2,820
Mortgage servicing rights	62,994	53,208
Total financial assets	89,875	83,376
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans, net of allowance for credit losses	24,145	27,348
OREO	2,736	2,820
Mortgage servicing rights	62,994	53,208
Total financial assets	$ 89,875	$ 83,376