Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Commercial Loans Held-for-sale, Fair Value Disclosure	$ 30,452		$ 0
Mortgage servicing rights	67,872		58,384
Mortgage Servicing Rights (MSR) Impairment (Recovery)	(669)	$ 286
Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Commercial Loans Held-for-sale, Fair Value Disclosure	30,452		0
Residential Held-for-sale, Fair Value Disclosure	134,361		85,544
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Other Real Estate Owned Fair Value Disclosure	2,688		2,604
Foreclosure / OREO expense, net	(965)		(939)
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Impaired loans	39,438		92,534
Provision for Credit Losses, Impaired Loans	(13,183)		(32,159)
Mortgage servicing rights	87,120		64,387
Mortgage Servicing Rights (MSR) Impairment (Recovery)	$ 669		$ (175)