Notes Receivable (Narrative) (Details) (USD $) In Millions | Sep. 30, 2011 | Dec. 31, 2010 | ||||
|---|---|---|---|---|---|---|
| Total unsecured consumer installment loans, net of an allowance for loan losses | $ 439 | [1] | $ 386 | [1] | ||
| EnerBank's Loans classified as current Notes receivable | 62 | 70 | ||||
| EnerBank's Loans classified as noncurrent Notes receivable | 430 | 397 | ||||
EnerBank USA [Member] | ||||||
| Total unsecured consumer installment loans, net of an allowance for loan losses | 439 | 386 | ||||
| Allowance for loan losses | 5 | 5 | ||||
| EnerBank's Loans classified as current Notes receivable | 16 | 11 | ||||
| EnerBank's Loans classified as noncurrent Notes receivable | $ 423 | $ 375 | ||||
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