Derivative Instruments and Hedging Activities (Schedule of Interest Rate Contracts) (Details) $ in Millions	Jun. 30, 2018 USD ($)
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, fixed interest rate	1.58%
Designated as Hedging Instrument [Member] \| Interest Rate Swap One [Member]
Derivative [Line Items]
Derivative, notional amount	$ 656.3
Derivative, fixed interest rate	0.98%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Two [Member]
Derivative [Line Items]
Derivative, notional amount	$ 300.0
Derivative, fixed interest rate	1.29%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Three [Member]
Derivative [Line Items]
Derivative, notional amount	$ 300.0
Derivative, fixed interest rate	2.08%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Four [Member]
Derivative [Line Items]
Derivative, notional amount	$ 200.0
Derivative, fixed interest rate	1.62%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Five [Member]
Derivative [Line Items]
Derivative, notional amount	$ 200.0
Derivative, fixed interest rate	1.40%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Six [Member]
Derivative [Line Items]
Derivative, notional amount	$ 200.0
Derivative, fixed interest rate	1.53%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Seven [Member]
Derivative [Line Items]
Derivative, notional amount	$ 100.0
Derivative, fixed interest rate	1.50%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Eight [Member]
Derivative [Line Items]
Derivative, notional amount	$ 100.0
Derivative, fixed interest rate	1.52%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Nine [Member]
Derivative [Line Items]
Derivative, notional amount	$ 200.0
Derivative, fixed interest rate	1.57%
Designated as Hedging Instrument [Member] \| Interest Rate Swap Ten [Member]
Derivative [Line Items]
Derivative, notional amount	$ 75.0