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Employee Benefit Plans narrative (Details) - CAD CAD in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Jul. 01, 2016 | Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | CAD 2,208 | CAD 1,301 |  |
TECO Energy Inc [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | 1,180 | 1,089 | CAD 859 |
Pension Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
ABO for defined pension plans | 2,489 | 1,427 |  |
Defined Benefit Plan, Fair Value of Plan Assets | 2,208 | 1,300 |  | CAD 1,205
Pension Plan [Member] | TECO Energy Inc [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Contribution Amount | 17 | 9 |  |
Other Postretirement Benefit Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Fair Value of Plan Assets | CAD 39 | CAD 6 |  | CAD 5

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- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=64937038&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Plan Assets -URI http://asc.fasb.org/extlink&oid=6749337 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Plan Assets -URI http://asc.fasb.org/extlink&oid=6520858 + Details
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- Definition If aggregate disclosures are presented, the aggregate pension accumulated benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=73719040&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2417-114920 + Details
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- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
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