Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Mortgage servicing rights	$ 66,980		$ 58,384
Mortgage Servicing Rights (MSR) Impairment (Recovery)	(607)	$ 275
Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Residential Held-for-sale, Fair Value Disclosure	143,022		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	1,954		2,604
Foreclosure / OREO expense, net	(808)		(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	52,972		92,534
Provision for Credit Losses, Impaired Loans	12,431		32,159
Mortgage servicing rights	84,585		64,387
Mortgage Servicing Rights (MSR) Impairment (Recovery)	$ 607		$ (175)