SCHEDULE I - CONDENSED PARENT COMPANY FINANCIAL STATEMENTS STATEMENTS OF CASH FLOWS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities
Net income (loss) attributed to common shareholders	$ 351.8	$ 281.4	$ 227.4
Adjustments to reconcile net income to net cash provided by operating activities
Discontinued operations, net of tax	(4.8)	9.7	(0.5)
Equity earnings from subsidiaries	(19.2)	(17.5)	(14.8)
Dividends from subsidiaries	191.6
Other	41.0	20.1	45.9
Changes in working capital
Accounts receivable	(358.8)	(26.2)	93.4
Other current assets	(42.0)	6.1	55.3
Accounts payable	143.1	22.0	(37.3)
Other current liabilities	45.1	23.1	(86.8)
Net cash provided by operating activities	555.0	569.0	717.8
Investing activities
Net cash used for investing activities	(1,024.3)	(605.0)	(393.5)
Financing activities
Issuance of long-term debt	1,174.0	428.0	50.0
Repayment of long-term debt	(363.5)	(278.2)	(565.8)
Proceeds from stock option exercises	38.7	55.8	10.3
Shares purchased for stock-based compensation	(2.0)	(89.9)	(17.0)
Dividends paid on common stock	(202.6)	(211.9)	(206.4)
Other	(16.6)	(1.0)	(7.5)
Net cash provided by (used for) financing activities	462.7	55.1	(478.1)
Net change in cash and cash equivalents	(5.1)	(0.7)	(150.9)
Cash and cash equivalents at beginning of year	27.4	28.1	179.0
Cash and cash equivalents at end of year	22.3	27.4	28.1
Supplemental cash flow information
Cash paid for interest	116.1	109.7	130.7
Cash received for income taxes	(4.8)	(47.6)	(80.0)
Integrys Energy Group, Inc.
Operating activities
Net income (loss) attributed to common shareholders	351.8	281.4	227.4
Adjustments to reconcile net income to net cash provided by operating activities
Discontinued operations, net of tax	(4.8)	9.7	(0.5)
Equity earnings from subsidiaries	(397.1)	(332.4)	(275.5)
Dividends from subsidiaries	169.6	163.9	461.3
Deferred income taxes	26.2	8.6	29.2
Other	4.0	4.2	3.5
Changes in working capital
Accounts receivable	(0.7)	0.4	(0.6)
Accounts receivable from related parties	0.6	1.0	0.9
Receivable from related parties	0	0	13.8
Other current assets	(7.9)	29.0	12.8
Accounts payable	0.6	(0.5)	0
Accounts payable to related parties	(0.2)	(0.4)	(5.0)
Other current liabilities	(2.9)	(3.2)	15.9
Net cash provided by operating activities	139.2	161.7	483.2
Investing activities
Short-term notes receivable from related parties	(50.4)	(12.1)	33.3
Issuance of long-term notes receivable from related parties	(35.0)	0	(10.0)
Repayment of long-term notes receivable from related parties	44.5	1.3	1.3
Equity contributions to subsidiaries	(234.6)	(89.9)	(63.2)
Return of capital from subsidiaries	75.0	110.5	229.8
Net cash used for investing activities	(200.5)	9.8	191.2
Financing activities
Commercial paper, net	(85.2)	115.8	92.6
Short-term notes payable to related parties	(92.3)	76.2	(305.2)
Repayment of long-term notes payable to related parties	0	(21.0)	(325.0)
Issuance of long-term debt	400.0	0	0
Repayment of long-term debt	0	(100.0)	(30.2)
Proceeds from stock option exercises	38.7	55.8	10.3
Shares purchased for stock-based compensation	0	(75.3)	(9.1)
Issuance of common stock	19.2	0	7.3
Dividends paid on common stock	(202.6)	(211.9)	(206.4)
Other	(18.8)	(10.4)	(7.4)
Net cash provided by (used for) financing activities	59.0	(170.8)	(773.1)
Net change in cash and cash equivalents	(2.3)	0.7	(98.7)
Cash and cash equivalents at beginning of year	2.6	1.9	100.6
Cash and cash equivalents at end of year	0.3	2.6	1.9
Supplemental cash flow information
Cash paid for interest	44.4	44.4	44.6
Cash paid for interest - related parties	0.7	1.4	6.8
Cash received for income taxes	$ (3.0)	$ (24.1)	$ (46.3)