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- Definition

The interest rate used to adjust for the time value of money for the plan.

+ 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 (k)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

Expected rate of compensation increases (for pay-related plans).

+ 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 (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

The interest rate used to adjust for the time value of money.

+ References

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
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- Definition

Expected rate of compensation increases (for pay-related plans).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- References

No definition available.

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- Definition

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

+ 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 (m)
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Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 50
-Paragraph 1
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- Definition

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 50
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- Definition

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

+ 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 (m)
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- Definition

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Health Care Cost Trend Rate
-URI http://asc.fasb.org/extlink&oid=6514820

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- Definition

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The ultimate trend rate for health care costs.

+ 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 (l)
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- References

No definition available.

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- Definition

Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested during next fiscal year.

+ References

No definition available.

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Employee Benefits - Assumptions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Weighted average assumptions used
Discount rate	4.16%	4.46%
Rate of compensation increase	3.60%	4.00%
Discount rate	4.35%	4.11%	5.00%
Expected return on plan assets	7.12%	7.37%	7.25%
Rate of compensation increase	3.75%	4.00%	4.00%
Expected return on assets during next fiscal year	7.11%
OPEB
Weighted average assumptions used
Discount rate	4.14%	4.38%
Assumed medical cost trend rate (as a percent)	7.00%	7.50%
Ultimate trend rate (as a percent)	5.00%	5.00%
Year ultimate trend rate is reached	2021	2021
Discount rate	4.38%	4.09%	4.95%
Expected return on plan assets	7.25%	7.54%	7.50%
Expected return on assets during next fiscal year	7.25%
Effects of a one-percentage-point change in assumed health care cost trend rates
Effect of one-percentage-point increase on total of service and interest cost components of net periodic postretirement health care benefit cost	$ 8.5
Effect of one-percentage-point decrease on total of service and interest cost components of net periodic postretirement health care benefit cost	(6.9)
Effect of one-percentage-point increase on the health care component of the accumulated postretirement benefit obligation	49.6
Effect of one-percentage-point decrease on the health care component of the accumulated postretirement benefit obligation	$ (39.5)
OPEB \| Maximum
Weighted average assumptions used
Assumed medical cost trend rate (as a percent)	7.50%	7.50%	7.50%
Ultimate trend rate (as a percent)	5.00%	5.00%	5.00%
Year ultimate trend rate is reached	2021	2021	2021
Wisconsin Energy \| Pension Benefits \| Equity securities:
Target asset allocations
Target asset allocations (as a percent)	35.00%
Wisconsin Energy \| Pension Benefits \| Fixed income securities:
Target asset allocations
Target asset allocations (as a percent)	55.00%
Wisconsin Energy \| Pension Benefits \| Private equity funds
Target asset allocations
Target asset allocations (as a percent)	10.00%
Wisconsin Energy \| OPEB \| Equity securities:
Target asset allocations
Target asset allocations (as a percent)	60.00%
Wisconsin Energy \| OPEB \| Fixed income securities:
Target asset allocations
Target asset allocations (as a percent)	40.00%
Integrys Holding Inc \| Pension Benefits \| Equity securities:
Target asset allocations
Target asset allocations (as a percent)	60.00%
Integrys Holding Inc \| Pension Benefits \| Fixed income securities:
Target asset allocations
Target asset allocations (as a percent)	40.00%
Integrys Holding Inc \| OPEB \| Equity securities:
Target asset allocations
Target asset allocations (as a percent)	45.00%
Integrys Holding Inc \| OPEB \| Equity securities: \| Maximum
Target asset allocations
Target asset allocations (as a percent)	50.00%
Integrys Holding Inc \| OPEB \| Fixed income securities:
Target asset allocations
Target asset allocations (as a percent)	50.00%
Integrys Holding Inc \| OPEB \| Fixed income securities: \| Maximum
Target asset allocations
Target asset allocations (as a percent)	55.00%