Derivative Financial Instruments (Interest Rate Cap Derivative Summary) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Interest Rate Cap Seventy Seven Million Notional May Two Thousand Fifteen Maturity [Member] | Derivatives Not Designed as Hedging Instruments Under ASC 815 [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	$ 77,000
Interest Rate Derivatives, at Fair Value, Net	0
Interest Rate Cap Two Hundred Fifteen Million Notional May Two Thousand Sixteen Maturity [Member] | Derivatives Not Designed as Hedging Instruments Under ASC 815 [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	215,000
Interest Rate Derivatives, at Fair Value, Net	97
Interest Rate Cap Ninety Six Million Five Hundred Thirty Thousand Notional April Two Thousand Fifteen Maturity [Member] | Derivatives Not Designed as Hedging Instruments Under ASC 815 [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	96,530
Interest Rate Derivatives, at Fair Value, Net	0
Interest Rate Cap Two Hundred Sixteen Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	216,500
Interest Rate Derivatives, at Fair Value, Net	301
Interest Rate Cap Fifty Six Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity [Member] | Derivatives Not Designed as Hedging Instruments Under ASC 815 [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	56,500
Interest Rate Derivatives, at Fair Value, Net	106
Interest Rate Cap Forty Three Million Five Hundred Thousand Notional August Two Thousand Sixteen Maturity [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	43,500
Interest Rate Derivatives, at Fair Value, Net	82
Interest Rate Cap One Hundred Million Notional March Two Thousand Seventeen Maturity [Member] | Derivatives Not Designed as Hedging Instruments Under ASC 815 [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	100,000
Interest Rate Derivatives, at Fair Value, Net	587
Interest Rate Cap Seventy Five Million Notional November Two Thousand Sixteen Maturity [Member] | Derivatives Not Designed as Hedging Instruments Under ASC 815 [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	75,000
Interest Rate Derivatives, at Fair Value, Net	240
Interest Rate Cap Fifty Million Notional September Two Thousand Seventeen Maturity [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	50,000
Interest Rate Derivatives, at Fair Value, Net	548
Interest Rate Cap Forty Million Notional September Two Thousand Seventeen Maturity [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	40,000
Interest Rate Derivatives, at Fair Value, Net	459
Total Interest Rate Cap [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	970,030
Interest Rate Derivatives, at Fair Value, Net	2,420
Total Interest Rate Cap [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	350,000
Interest Rate Derivatives, at Fair Value, Net	$ 1,390