SCHEDULE I - CONDENSED PARENT COMPANY FINANCIAL STATEMENTS (Details 9) (INTEGRYS ENERGY GROUP, INC., USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2010 Long-term notes due 2011 PELLC	Sep. 28, 2007 Long-term notes due 2011 PELLC	Dec. 31, 2011 Long-term notes due 2021 Integrys Energy Services	Dec. 31, 2010 Long-term notes due 2021 Integrys Energy Services
LONG-TERM NOTES PAYABLE - RELATED PARTIES
Long-term notes payable - related parties	$ 21.0	$ 346.0	$ 325.0	$ 325.0	$ 21.0	$ 21.0
Less current portion		(325.0)
Total long-term notes payable - related parties	21.0	21.0
Interest rate stated percentage				5.25%
Schedule of all principal debt payment amounts related to bond maturities
Later years	21.0
Total payments	$ 21.0	$ 21.0