Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant, and Equipment

Property, plant, and equipment consisted of the following as of December 31:

		MGE Energy				MGE
(In thousands)		2019		2018		2019		2018
Utility:
Electric(a)(b)	$	1,480,684	$	1,310,421	$	1,480,701	$	1,310,438
Gas		472,123		442,581		472,134		442,593
Total utility plant		1,952,807		1,753,002		1,952,835		1,753,031
Less: Accumulated depreciation and amortization(b)		674,251		639,486		674,251		639,486
In-service utility plant, net		1,278,556		1,113,516		1,278,584		1,113,545
Nonregulated:
Nonregulated		323,266		322,855		323,266		322,855
Less: Accumulated depreciation and amortization		71,623		66,605		71,623		66,605
In-service nonregulated plant, net		251,643		256,250		251,643		256,250
Construction work in progress:
Utility construction work in progress(a)(b)(c)		111,707		138,663		111,707		138,663
Nonregulated construction work in progress		777		1,008		777		1,008
Total property, plant, and equipment	$	1,642,683	$	1,509,437	$	1,642,711	$	1,509,466

(a)In December 2017, a one-time tax impact, as a result of the Tax Act, decreased income tax provision and transmission investment $21.7 million and $20.4 million, respectively.

(b)Includes long-term debt due within one year, debt issuance costs, and unamortized discount.