Revenue Recognition - Renewable Energy (Details)	3 Months Ended
Mar. 31, 2018
Minimum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Term of power purchase agreements with various customers (in years)	10 years
Maximum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Term of power purchase agreements with various customers (in years)	25 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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