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Subsequent Event Subsequent Event (Details) $ / shares in Units, $ in Thousands, customers in Millions, CAD in Billions |  | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | --- | ---
Jul. 19, 2017 CAD customers | Jun. 30, 2017 USD ($) | Jun. 30, 2016 USD ($) | Jun. 30, 2017 USD ($) | Jun. 30, 2016 USD ($) | Jul. 19, 2017 USD ($) customers $ / shares | Dec. 31, 2016 USD ($)
Business Acquisition [Line Items] |  |  |  |  |  |  |
Hydro One Total Assets |  | $ 5,373,004 |  | $ 5,373,004 |  |  | $ 5,309,755
Hydro One Total Annual Revenues |  | $ 314,501 | $ 318,838 | $ 750,971 | $ 737,011 |  |
Subsequent Event [Member] | Hydro One [Member] |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Hydro One Number of Customers | customers | 1.3 |  |  |  |  | 1.3 |
Business Acquisition, Share Price | $ / shares |  |  |  |  |  | $ 53.00 |
Termination Fee Payable By Company |  |  |  |  |  | $ 103,000 |
Subsequent Event [Member] | Canada, Dollars | Hydro One [Member] |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Hydro One Total Assets | CAD | CAD 25.0 |  |  |  |  |  |
Hydro One Total Annual Revenues | CAD | CAD 6.5 |  |  |  |  |  |

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- Definition Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(12)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(11)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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