Derivative Financial Instruments (Schedule of Cash Flow Hedging Derivatives) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Total Interest Rate Cap [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	$ 2,420
Derivative, Notional Amount	970,030
Cash Flow Hedging [Member] | Interest Rate Swap Fifty Million Notional September Two Thousand Sixteen Maturity [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	(1,310)
Derivative, Notional Amount	50,000
Cash Flow Hedging [Member] | Interest Rate Swap Twenty Five Million Notional October Two Thousand Sixteen Maturity [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	(684)
Derivative, Notional Amount	25,000
Cash Flow Hedging [Member] | Total Interest Rate Swaps [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	(1,994)
Derivative, Notional Amount	75,000
Cash Flow Hedging [Member] | Interest Rate Cap Forty Three Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	82
Derivative, Notional Amount	43,500
Cash Flow Hedging [Member] | Interest Rate Cap Two Hundred Sixteen Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	301
Derivative, Notional Amount	216,500
Cash Flow Hedging [Member] | Interest Rate Cap Fifty Million Notional September Two Thousand Seventeen Maturity [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	548
Derivative, Notional Amount	50,000
Cash Flow Hedging [Member] | Interest Rate Cap Forty Million Notional September Two Thousand Seventeen Maturity [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	459
Derivative, Notional Amount	40,000
Cash Flow Hedging [Member] | Total Interest Rate Cap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	1,390
Derivative, Notional Amount	350,000
Cash Flow Hedging [Member] | Interest Rate Swaps And Caps [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Fair Value Gain (Loss)	(604)
Derivative, Notional Amount	$ 425,000