Fair Value Measurements and Disclosures Concentration of Risk (Details) (USD $)	Sep. 30, 2013
Concentration Risk [Line Items]
Fair Value of Derivative Assets	$ 15,582,000
Number of derivative counterparties not lenders in our revolving credit facility	20
JPMorgan Chase Bank
Concentration Risk [Line Items]
Fair Value of Derivative Assets	4,163,000	[1]
Wells Fargo Bank
Concentration Risk [Line Items]
Fair Value of Derivative Assets	3,830,000	[1]
Natixis
Concentration Risk [Line Items]
Fair Value of Derivative Assets	1,637,000	[1]
Bank of Montreal
Concentration Risk [Line Items]
Fair Value of Derivative Assets	1,885,000	[1]
BNP Paribas
Concentration Risk [Line Items]
Fair Value of Derivative Assets	1,285,000	[1]
Other Lenders in Our Credit Facility
Concentration Risk [Line Items]
Fair Value of Derivative Assets	2,624,000
Various
Concentration Risk [Line Items]
Fair Value of Derivative Assets	$ 158,000	[2]

[1] Major lender in our revolving credit facility. See Note 7, Long-Term Debt.

[2] Represents a total of 20 counterparties.