Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Mortgage servicing rights	$ 67,306	$ 68,193	$ 58,384
Mortgage Servicing Rights (MSR) Impairment (Recovery)	63	(545)	$ 175
Equity Securities without Readily Determinable Fair Value, Amount	13,000	0
Equity securities	15,090	1,568
Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Equity Securities without Readily Determinable Fair Value, Amount	13,444	0
Equity securities	13,444	0
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
OREO(c)	3,565	2,200
Other noninterest expense	(1,860)	(1,545)
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Impaired loans	45,792	26,191
Provision for Credit Losses, Impaired Loans	(66,172)	(14,521)
Mortgage servicing rights	72,532	81,012
Mortgage Servicing Rights (MSR) Impairment (Recovery)	(63)	$ 545
Equity Securities without Readily Determinable Fair Value, Amount	13,444
Equity securities	$ 13,444