Fair Value Measurements (Nonrecurring Basis) (Details) - Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	$ 73,518	$ 63,572
Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	73,518	63,572
Impaired loans
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis		62,184
Impaired loans | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	70,619	62,184
Other real estate and repossessed assets
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	2,899	1,386
Other real estate and repossessed assets | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	$ 2,899	1,386
Loan servicing rights
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis		2
Loan servicing rights | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis		$ 2