Pension Plan and Employee Benefits, Pension Plan Asset Investment Objectives (Details)	12 Months Ended
Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Maximum notional value of derivative positions of the total pension fund's value	20.00%
Pension Benefits [Member] \| Domestic equity [Member]
Investment asset allocation target percentage of total plan assets [Abstract]
Target plan allocations	16.00%
Pension Benefits [Member] \| International equity [Member]
Investment asset allocation target percentage of total plan assets [Abstract]
Target plan allocations	16.00%
Pension Benefits [Member] \| Real estate funds [Member]
Investment asset allocation target percentage of total plan assets [Abstract]
Target plan allocations	7.00%
Pension Benefits [Member] \| Hedge Funds [Member]
Investment asset allocation target percentage of total plan assets [Abstract]
Target plan allocations	1.00%
Pension Benefits [Member] \| Return Seeking [Member]
Investment asset allocation target percentage of total plan assets [Abstract]
Target plan allocations, minimum	35.00%
Target plan allocations	40.00%
Target plan allocations, maximum	45.00%
Pension Benefits [Member] \| Fixed income- long government/credit [Member]
Investment asset allocation target percentage of total plan assets [Abstract]
Target plan allocations	20.00%
Pension Benefits [Member] \| Fixed income- long credit [Member]
Investment asset allocation target percentage of total plan assets [Abstract]
Target plan allocations	40.00%
Pension Benefits [Member] \| Liability Hedging [Member]
Investment asset allocation target percentage of total plan assets [Abstract]
Target plan allocations, minimum	55.00%
Target plan allocations	60.00%
Target plan allocations, maximum	64.00%

Maximum notional value of derivative positions of the total pension fund's value

No definition available.

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- Details

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- Definition

Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

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Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

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Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

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