Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2013
Accounting Policies [Abstract]
Comprehensive Income [Policy Text Block]	Comprehensive Income Comprehensive income is the change in common shareholders’ equity during a period from transactions and events from non-owner sources, including net income. As shown in the following tables, amounts recorded to accumulated other comprehensive loss for the three and six months ended June 30, 2013 include unrealized gains and losses from derivatives accounted for as cash flow hedges, unrealized gains and losses on available-for-sale securities and the Company’s interest in other comprehensive income of equity investees, which comprise the net unrealized gains and losses on investments, changes in benefit obligations, consisting of deferred actuarial losses, prior service costs and transition amounts related to pension and other postretirement benefit plans, and foreign currency translation adjustments.
Intangible Assets	Emission allowances and renewable energy credits are charged to expense, using average cost, as the allowances and credits are consumed in the operation of the business. The Company amortizes contract intangible assets on a straight-line basis over the expected period of benefit, ranging from 3 to 28 years.
Income Tax [Policy Text Block]	Income Taxes The Company's effective tax rate from continuing operations for the three months ended June 30, 2013 was 29 percent as compared to 32 percent for the three months ended June 30, 2012. The Company's effective tax rate from continuing operations for the six months ended June 30, 2013 was 30 percent as compared to 32 percent for the six months ended June 30, 2012. The decrease in the effective tax rate in 2013 is due primarily to higher production tax credits. The Company had $3 million of unrecognized tax benefits at June 30, 2013, that, if recognized, would favorably impact its effective tax rate. The Company believes that it is possible that there will be a decrease in the unrecognized tax benefits of up to $1 million in the next twelve months.

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

+ References+ Details