Derivative Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative [Line Items]
Derivative, Notional Amount	$ 300,000
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	10,852	$ (129)
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	100,000
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	200,000
Other Nonoperating Income (Expense) [Member] | Other Contract [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	11,117	$ 0
Other Expense [Member] | Other Contract [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 8,913