Derivative Financial Instruments Interest Rate Cap Derivative Summary (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	$ 315,000
Interest Rate Caps 1 [Member] | Cash Flow Hedges [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	20,000
Interest Rate Derivatives, at Fair Value, Net	1
Interest Rate Caps 2 [Member] | Cash Flow Hedges [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	40,000
Interest Rate Derivatives, at Fair Value, Net	1
Interest Rate Non-Hedging Cap 1 [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	77,000
Interest Rate Derivatives, at Fair Value, Net	43
Interest Rate Non-Hedging Cap 2 [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	215,000
Interest Rate Derivatives, at Fair Value, Net	983
Interest Rate Non-Hedging Cap 3 [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	96,530
Interest Rate Derivatives, at Fair Value, Net	91
Interest Rate Non-Hedging Cap 4 [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	216,500
Interest Rate Derivatives, at Fair Value, Net	1,568
Interest Rate Non-Hedging Cap 5 [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	100,000
Interest Rate Derivatives, at Fair Value, Net	852
Interest Rate Non-Hedging Cap 6 [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	100,000
Interest Rate Derivatives, at Fair Value, Net	1,573
Interest Rate Non-Hedging Cap 7 [Member] | Not Designated as Hedging Instrument [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	75,000
Interest Rate Derivatives, at Fair Value, Net	834
Interest Rate Caps 3 [Member] | Cash Flow Hedges [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	50,000
Interest Rate Derivatives, at Fair Value, Net	1,175
Interest Rate Caps 4 [Member] | Cash Flow Hedges [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	40,000
Interest Rate Derivatives, at Fair Value, Net	969
Total Interest Rate Cap [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	1,030,030
Interest Rate Derivatives, at Fair Value, Net	8,090
Total Interest Rate Cap [Member] | Cash Flow Hedges [Member]
Interest Rate Cap Derivative Summary [Line Items]
Derivative, Notional Amount	150,000
Interest Rate Derivatives, at Fair Value, Net	$ 2,146