Financial Instruments with Off-Balance Sheet Risk (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) contract	Dec. 31, 2016 USD ($)
Derivative [Line Items]
Interest Rate Derivative Assets, at Fair Value	$ 4,600,000	$ 5,000,000
Interest Rate Derivative Liabilities, at Fair Value	$ 3,200,000	3,200,000
Maximum Length of Time Hedged in Cash Flow Hedge	10 months
Reclassifications into Interest expense on cash flow hedge	$ 0
Expected reclassifications into interest expense on cash flow hedge in next twelve months	0
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	1,400,000
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness	0
Reclassifications into earnings on cash flow hedge	0
Fair Value of Interest Rate Swaps	$ 3,000,000	3,200,000
Interest Rate Swap
Derivative [Line Items]
Derivative, Number of Instruments Held | contract	7
Notional Amount of Interest Rate Derivatives	$ 60,000,000
Commercial Portfolio Segment [Member] | Interest Rate Swap
Derivative [Line Items]
Notional Amount of Interest Rate Derivatives	$ 363,300,000	$ 247,300,000