Mortgage Servicing Rights (Amortization method rollforward) (Details 3) - Mortgage Servicing Rights - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Mortgage Servicing Rights Accounted for Under the Amortization Method {Rollforward)
Balance at Beginning of Period	$ 23,168	$ 22,008
Servicing Rights that Resulted From Asset Transfers	621	1,315
Amortization	(700)	(618)
Balance at End of Period	23,089	22,705
Fair Value of Mortgage Servicing Rights Accounted for Under the Amortization Method
Beginning of Period	26,716	25,148
End of Period	$ 28,600	$ 25,946