SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES CASH AND CASH EQUIVALENTS (Details)	12 Months Ended
Dec. 31, 2014
Cash and cash equivalents
Maximum maturity of short-term investments to classify instruments as cash equivalents	3 months

Maximum term of original maturity to classify an instrument as a cash equivalent.

No definition available.

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Namespace Prefix:	wps_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration