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Investment in ATC - FERC Complaints (Details) - Jun. 30, 2015 $ in Millions | USD ($)
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Sensitivity Analysis [Member] |
Sensitivity Analysis [Line Items] |
Basis Point Reduction on Approved Rate of Return on Common Equity | 50
FERC Complaint 1 [Member] |
Loss Contingencies [Line Items] |
Equity Method Investment, Proposed Return on Common Equity | 9.15%
FERC Complaint 2 [Member] |
Loss Contingencies [Line Items] |
Equity Method Investment, Proposed Return on Common Equity | 8.67%
Rainy River Energy [Member] |
Loss Contingencies [Line Items] |
Loss Contingency, Accrual Reflected in Equity Earnings | $ 1.7
Rainy River Energy [Member] | FERC Complaint 2 [Member] |
Loss Contingencies [Line Items] |
Loss Contingency, Accrual Reflected in Equity Earnings | 1.1
After-tax [Member] | Sensitivity Analysis [Member] |
Sensitivity Analysis [Line Items] |
Effect on Future Earnings, Amount | 0.5
Pre-tax [Member] | Sensitivity Analysis [Member] |
Sensitivity Analysis [Line Items] |
Effect on Future Earnings, Amount | $ 0.9

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