Derivative Financial Instruments (Narrative) (Details) - Interest Rate Swap [Member] $ in Thousands	Dec. 31, 2016 USD ($)
Derivative [Line Items]
Derivative, Notional Amount	$ 300,000
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative, Notional Amount	200,000
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 100,000