Borrowings Repurchase Agreements and Other Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Securities Sold Under Agreements to Repurchase Weighted Average Rate	0.0951%
Securities Sold under Agreements to Repurchase	$ 155,388	$ 185,763
Securities Sold under Agreements to Repurchase Increase (Decrease)	(30,400)
Securities Sold under Agreements to Repurchase [Member]
Short-term Debt [Line Items]
Maximum outstanding at any month-end	163,626	185,763	$ 128,842
Average amount outstanding for the year	$ 144,674	$ 129,734	$ 113,748