Acquisitions (Details) - MBT Bancshares [Member] - USD ($) $ in Thousands		9 Months Ended
	Dec. 01, 2016	Sep. 30, 2017
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Dec. 01, 2016
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	$ 102,500
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles		$ 2,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment		1,500
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Goodwill		$ 526