Derivative and Hedging Activities (Assets and liabilities measured at fair value) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
In the next 12 months will be reclassified as an increase to interest expense	$ 712
Interest Rate Swap | Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative asset	4,321	$ 875
Interest Rate Swap | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative asset	0	0
Interest Rate Swap | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative asset	4,321	875
Interest Rate Swap | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative asset	0	0
Interest Rate Swap | Other assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative asset	4,321	$ 875
Interest Rate Swap Maturing 1/31/2019 | Bank of Montreal | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, notional amount	50,000
Interest Rate Swap Maturing 1/31/2019 | Regions Bank | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, notional amount	50,000
Interest Rate Swap Maturing 8/31/2022 | Bank of Montreal | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, notional amount	100,000
Interest Rate Swap Maturing 8/31/2022 | U.S. Bank | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, notional amount	$ 100,000