Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Mortgage servicing rights	$ 68,193	$ 58,384	$ 61,476
Mortgage Servicing Rights (MSR) Impairment (Recovery)	(545)	175	$ (200)
Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Commercial loans held for sale	14,943	0
Mortgage loans held for sale	64,321	85,544
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Other real estate owned (c)	2,200	2,604
Foreclosure / OREO expense, net	(1,545)	(939)
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Impaired loans	26,191	92,534
Provision for Credit Losses, Impaired Loans	(14,521)	(32,159)
Mortgage servicing rights	81,012	64,387
Mortgage Servicing Rights (MSR) Impairment (Recovery)	$ 545	$ (175)