Number of joint ventures in which the Company has an interest.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the proportionate consolidation method.

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Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold, or consumed within one year (or the normal operating cycle, if longer). Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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For an unclassified balance sheet, amounts due from an entity in which the reporting entity shares joint control with another party or group.

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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Total obligations incurred as part of normal operations that are expected to be paid during the following twelve months or within one business cycle, if longer.

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Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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The cash outflow from advancing money to an affiliate (an entity that is related but not strictly controlled by the entity).

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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.

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No definition available.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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Related Party Transactions (Contractual Joint Ventures) (Narrative) (Details) CAD in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 CAD	Sep. 30, 2016 USD ($)	Dec. 31, 2015 CAD	Dec. 31, 2015 USD ($)
Related Party Transaction [Line Items]
Current assets						$ 1,422,427,000		$ 1,129,758,000
Current liabilities						942,365,000		752,535,000
Performance Guarantees [Member]
Related Party Transaction [Line Items]
Guarantees issued, related parties						$ 122,400,000		539,300,000
Joint Venture [Member] \| Joint Ventures That Provide Electrical Transmission Infrastructure Services [Member]
Related Party Transaction [Line Items]
Number of proportionately consolidated joint ventures					2	2
Current assets						$ 9,200,000
Current liabilities						$ 7,100,000
Joint Venture [Member] \| Joint Ventures That Provide Electrical Transmission Infrastructure Services [Member] \| Maximum [Member]
Related Party Transaction [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage					90.00%	90.00%
Joint Venture [Member] \| Joint Ventures That Provide Electrical Transmission Infrastructure Services [Member] \| Minimum [Member]
Related Party Transaction [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage					85.00%	85.00%
Joint Venture [Member] \| Pacer [Member]
Related Party Transaction [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage					35.00%	35.00%
Joint Venture [Member] \| Pacer [Member] \| Performance Guarantees [Member]
Related Party Transaction [Line Items]
Guarantees issued, related parties \| CAD					CAD 132.1		CAD 132.1
Joint Venture [Member] \| Pacer [Member] \| Canadian Dollars [Member]
Related Party Transaction [Line Items]
Revenue, related party	$ 200,000	$ 300,000	$ 800,000	$ 1,800,000
Joint Venture [Member] \| Pacer [Member] \| Canadian Dollars [Member] \| Financing Support [Member]
Related Party Transaction [Line Items]
Project-related financing provided, related party	$ 800,000		$ 5,600,000
Contractual joint venture, additional amounts committed						$ 0
Joint Venture [Member] \| Pacer [Member] \| Canadian Dollars [Member] \| Performance Guarantees [Member]
Related Party Transaction [Line Items]
Guarantees issued, related parties						100,600,000		95,400,000
Joint Venture [Member] \| Pacer [Member] \| Canadian Dollars [Member] \| Accounts Receivable [Member]
Related Party Transaction [Line Items]
Receivables, joint venture						$ 600,000		$ 1,200,000