Madison Gas and Electric Company Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Items not affecting cash:
Depreciation and amortization	$ 38,707	$ 40,942	$ 37,960
Deferred income taxes	44,797	33,698	25,381
Provision for doubtful receivables	2,498	2,312	2,805
Employee benefit plan expenses	18,353	13,703	14,748
Equity earnings in ATC	(9,079)	(8,615)	(8,501)
Gain on sale of property	(201)	(112)	(3,153)
Other items	1,484	1,728	2,254
Changes in working capital items:
Receivable - margin account (change)	3,726	(2,609)	1,159
Trade and other receivables (change)	(6,208)	173	(8,191)
Inventories (change)	1,457	7,438	3,755
Unbilled revenues (change)	(2,508)	3,466	(41)
Prepaid taxes (change)	2,731	245	7,540
Other current assets (change)	367	538	(977)
Accounts payable (change)	(272)	2,055	(2,895)
Other current liabilities (change)	425	(4,300)	(4,195)
Dividend income from ATC	7,146	6,728	6,667
Cash contributions to pension and other postretirement plans	(28,857)	(23,670)	(16,901)
Other noncurrent items, net	6,992	(3,876)	8,900
Cash Provided by (Used for) Operating Activities	146,004	130,772	124,033
Investing Activities:
Capital expenditures	(98,435)	(65,176)	(60,082)
Capital contributions to investments	(2,419)	(1,008)	(810)
Purchase of investment - land	(3)	(2,152)	0
Proceeds from sale of property	201	112	3,358
Other investing	(697)	1,873	149
Cash Provided by (Used for) Investing Activities	(101,353)	(66,351)	(57,385)
Financing Activities:
Cash dividends paid on common stock	(35,951)	(35,026)	(34,370)
Repayment of long-term debt	(30,668)	(2,500)	(16,527)
Issuance of long-term debt	28,000	30,000	80,000
Decrease in short-term debt	0	(22,500)	(92,000)
Other financing	(844)	(336)	(1,345)
Cash Provided by (Used for) Financing Activities	(39,463)	(30,362)	(64,242)
Change in Cash and Cash Equivalents:	5,188	34,059	2,406
Cash and cash equivalents at beginning of period	41,169	7,110	4,704
Cash and cash equivalents at end of period	46,357	41,169	7,110
Supplemental disclosures of cash flow information:
Interest paid	19,499	19,788	18,643
Income taxes paid	3,544	5,537	10,373
Income taxes received	(12,536)	(4,370)	(9,043)
Significant noncash investing activities [Abstract]
Accrued capital expenditures	10,317	684	762
MGE [Member]
Operating Activities:
Net Income	65,306	61,252	58,465
Items not affecting cash:
Depreciation and amortization	38,707	40,942	37,960
Deferred income taxes	44,112	32,773	24,354
Provision for doubtful receivables	2,498	2,312	2,805
Employee benefit plan expenses	18,353	13,703	14,748
Equity earnings in ATC	(9,079)	(8,615)	(8,501)
Gain on sale of property	(201)	(112)	(3,153)
Other items	2,014	2,284	2,788
Changes in working capital items:
Receivable - margin account (change)	3,726	(2,609)	1,159
Trade and other receivables (change)	(7,219)	1,183	(6,271)
Inventories (change)	1,457	7,438	3,755
Unbilled revenues (change)	(2,508)	3,466	(41)
Prepaid taxes (change)	(1,584)	(477)	(2,667)
Other current assets (change)	366	536	(978)
Accounts payable (change)	(1,658)	4,214	(2,913)
Accrued interest and taxes (change)	211	(3,741)	1,169
Other current liabilities (change)	(714)	(4,027)	(4,065)
Dividend income from ATC	7,146	6,728	6,667
Cash contributions to pension and other postretirement plans	(28,857)	(23,670)	(16,901)
Other noncurrent items, net	6,696	(3,897)	6,812
Cash Provided by (Used for) Operating Activities	138,772	129,683	115,192
Investing Activities:
Capital expenditures	(98,435)	(65,176)	(60,082)
Capital contributions to investments	(2,140)	(888)	(710)
Proceeds from sale of property	201	112	3,358
Other investing	(709)	230	(2)
Cash Provided by (Used for) Investing Activities	(101,083)	(65,722)	(57,436)
Financing Activities:
Cash dividends paid to parent by MGE	(20,404)	(26,648)	(26,150)
Distributions to parent from noncontrolling interest	(23,500)	(52,500)	(58,400)
Equity contribution received by noncontrolling interest	2,130	888	710
Affiliate financing of Elm Road	0	0	(4,193)
Repayment of long-term debt	(30,668)	(2,500)	(16,527)
Issuance of long-term debt	28,000	30,000	80,000
Decrease in short-term debt	0	(3,500)	(30,000)
Other financing	(795)	(297)	(1,176)
Cash Provided by (Used for) Financing Activities	(45,237)	(54,557)	(55,736)
Change in Cash and Cash Equivalents:	(7,548)	9,404	2,020
Cash and cash equivalents at beginning of period	13,898	4,494	2,474
Cash and cash equivalents at end of period	6,350	13,898	4,494
Supplemental disclosures of cash flow information:
Interest paid	19,499	19,731	18,363
Income taxes paid	44	28	3
Income taxes received	(448)	(10)	(5)
Significant noncash investing activities [Abstract]
Accrued capital expenditures	$ 10,317	$ 684	$ 762