Pension and Other Postretirement Plans

9 Months Ended

Sep. 30, 2017

Compensation and Retirement Disclosure [Abstract]

Pension and Other Postretirement Plans - MGE Energy and MGE.

MGE maintains qualified and nonqualified pension plans, health care, and life insurance benefits. Additionally, MGE has defined contribution 401(k) benefit plans.

The following table presents the components of net periodic benefit costs recognized for the three and nine months ended September 30, 2017 and 2016. A portion of the net periodic benefit cost is capitalized within the consolidated balance sheets.

		Three Months Ended				Nine Months Ended
		September 30,				September 30,
(In thousands)		2017		2016		2017		2016
Pension Benefits
Components of net periodic benefit cost:
Service cost	$	1,351	$	1,413	$	4,043	$	4,358
Interest cost		3,168		3,161		9,481		9,744
Expected return on assets		(5,762)		(5,724)		(17,244)		(17,646)
Amortization of:
Prior service (credit) cost		(4)		3		(12)		8
Actuarial loss		1,594		1,388		4,769		4,278
Net periodic benefit cost	$	347	$	241	$	1,037	$	742

Postretirement Benefits
Components of net periodic benefit cost:
Service cost	$	315	$	361	$	944	$	1,084
Interest cost		678		753		2,034		2,258
Expected return on assets		(722)		(787)		(2,165)		(2,360)
Amortization of:
Transition obligation		1		1		2		3
Prior service credit		(667)		(744)		(2,001)		(2,233)
Actuarial loss		190		178		570		533
Net periodic benefit credit	$	(205)	$	(238)	$	(616)	$	(715)