Subsequent Event (Details) $ in Thousands	Apr. 01, 2019 USD ($) branch shares	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Subsequent Event [Line Items]
Payments to Acquire Businesses, Gross	$ 167,400
Assets		$ 8,997,457	$ 8,851,592
Business Combination, Cost of Acquired Entity, Purchase Price	$ 667,100
Business Combination, Increase in Acquirer Outstanding Shares | shares	6,166,010
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Net	$ 2,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Investments	196,900
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	1,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Borrowings	$ 124,800
Number of Branches | branch	11