Fair Value Measurements and Disclosures Concentration of Risk (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Concentration Risk [Line Items]
Fair Value of Derivative Assets	$ 26,708
JPMorgan Chase Bank
Concentration Risk [Line Items]
Fair Value of Derivative Assets	9,730	[1]
Wells Fargo Bank
Concentration Risk [Line Items]
Fair Value of Derivative Assets	3,671	[1]
Natixis
Concentration Risk [Line Items]
Fair Value of Derivative Assets	2,924	[1]
Bank of Nova Scotia
Concentration Risk [Line Items]
Fair Value of Derivative Assets	2,680	[1]
Other Lenders in Our Credit Facility
Concentration Risk [Line Items]
Fair Value of Derivative Assets	6,754
Various
Concentration Risk [Line Items]
Fair Value of Derivative Assets	$ 949	[2]

[1] As of June 30, 2013 Derivatives instruments, recorded in condensed consolidated balance sheet, gross Effect of master netting agreements Derivative instruments, net Asset derivatives: Derivative instruments, at fair value $26,708 $(7,508) $19,200 Liability derivatives: Derivative instruments, at fair value $10,177 $(7,508) $2,669

[2] Represents a total of 23 counterparties.