Fair Value Measurements - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	$ 25,418	$ 21,686
OREO	2,911	4,319
Mortgage servicing rights	48,286
Total financial assets	76,615	26,005
Level 1
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	0	0
OREO	0	0
Mortgage servicing rights	0
Total financial assets	0	0
Level 2
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	0	0
OREO	0	0
Mortgage servicing rights	0
Total financial assets	0	0
Level 3
Impaired loans measured at fair value on a nonrecurring basis
Impaired loans	25,418	21,686
OREO	2,911	4,319
Mortgage servicing rights	48,286
Total financial assets	$ 76,615	$ 26,005