Madison Gas and Electric Company Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Items not affecting cash:
Depreciation and amortization	$ 56,412	$ 53,077	$ 44,646
Deferred income taxes	3,749	(4,082)	22,421
Provision for doubtful receivables	1,366	1,016	1,196
Employee benefit plan (credit) cost	(2,002)	831	295
Equity earnings in MGE Transco	(8,821)	(10,125)	(8,428)
Gain on sale of property	0	(1,547)	0
Other items	(814)	641	2,462
Changes in working capital items:
Trade and other receivables (change)	(2,235)	(4,502)	(3,594)
Inventories (change)	2,724	(2,568)	7,273
Unbilled revenues (change)	3,157	(1,554)	(4,838)
Prepaid taxes (change)	10,320	101	8,616
Other current assets (change)	251	(2,786)	15
Accounts payable (change)	(4,855)	(5,290)	9,881
Other current liabilities (change)	11,957	3,948	(1,738)
Dividend income from MGE Transco	6,958	8,803	5,854
Cash contributions to pension and other postretirement plans	(5,584)	(11,304)	(14,452)
Other noncurrent items, net	(3,762)	9,108	2,695
Cash Provided by Operating Activities	153,040	131,373	147,864
Investing Activities:
Capital expenditures	(212,197)	(108,131)	(83,659)
Capital contributions to investments	(5,926)	(11,081)	(2,958)
Proceeds from sale of property	0	2,819	0
Other	(205)	118	(196)
Cash Used for Investing Activities	(218,328)	(116,275)	(86,813)
Financing Activities:
Repayment of long-term debt	(24,453)	(34,358)	(4,267)
Issuance of long-term debt	100,000	70,000	0
Proceeds from short-term debt	9,000	4,000	0
Other	(662)	(597)	(70)
Cash Provided by (Used for) Financing Activities	38,123	(4,637)	(46,112)
Change in cash, cash equivalents, and restricted cash:	(27,165)	10,461	14,939
Cash, cash equivalents, and restricted cash at beginning of period	112,094	101,633	86,694
Cash, cash equivalents, and restricted cash at end of period	84,929	112,094	101,633
Supplemental disclosures of cash flow information:
Interest paid	20,018	19,176	19,415
Income taxes paid	12,597	27,149	21,831
Income taxes received	(59)	0	(10,000)
Significant noncash investing activities:
Accrued capital expenditures	11,129	16,602	16,376
MGE [Member]
Operating Activities:
Net Income	79,036	93,072	74,592
Items not affecting cash:
Depreciation and amortization	56,412	53,077	44,622
Deferred income taxes	(69)	(7,760)	20,876
Provision for doubtful receivables	1,366	1,016	1,196
Employee benefit plan (credit) cost	(2,002)	831	295
Equity earnings in MGE Transco	0	0	(6,366)
Gain on sale of property	0	(1,547)	0
Other items	(107)	1,408	2,990
Changes in working capital items:
Trade and other receivables (change)	(2,160)	(4,113)	(3,583)
Inventories (change)	2,724	(2,568)	7,273
Unbilled revenues (change)	3,157	(1,554)	(4,838)
Prepaid taxes (change)	9,283	725	8,481
Other current assets (change)	255	(2,788)	14
Accounts payable (change)	(4,817)	(5,312)	9,941
Accrued interest and taxes (change)	4,761	118	419
Other current liabilities (change)	9,685	1,941	(2,137)
Dividend income from MGE Transco	0	0	5,032
Cash contributions to pension and other postretirement plans	(5,584)	(11,304)	(14,452)
Other noncurrent items, net	(3,946)	8,878	2,497
Cash Provided by Operating Activities	147,994	124,120	146,852
Investing Activities:
Capital expenditures	(212,197)	(108,131)	(83,659)
Capital contributions to investments	0	0	(1,598)
Proceeds from sale of property	0	1,721	0
Other	(1,105)	(162)	(378)
Cash Used for Investing Activities	(213,302)	(106,572)	(85,635)
Financing Activities:
Cash dividends paid to parent by MGE	0	(45,000)	(50,000)
Distributions to parent from noncontrolling interest	(22,000)	(18,000)	(24,113)
Equity contribution received by noncontrolling interest	0	0	1,598
Repayment of long-term debt	(24,453)	(34,358)	(4,267)
Issuance of long-term debt	100,000	70,000	0
Proceeds from short-term debt	9,000	4,000	0
Other	(662)	(539)	(63)
Cash Provided by (Used for) Financing Activities	61,885	(23,897)	(76,845)
Change in cash, cash equivalents, and restricted cash:	(3,423)	(6,349)	(15,628)
Cash, cash equivalents, and restricted cash at beginning of period	10,093	16,442	32,070
Cash, cash equivalents, and restricted cash at end of period	6,670	10,093	16,442
Supplemental disclosures of cash flow information:
Interest paid	20,018	19,176	19,415
Income taxes paid	0	1	29
Income taxes received	(59)	0	0
Significant noncash investing activities:
Accrued capital expenditures	11,129	16,602	16,376
Dividend in kind to parent	$ 0	$ 0	$ 15,822