Pension and Other Postretirement Plans (Tables)

9 Months Ended

Sep. 30, 2013

Compensation and Retirement Disclosure [Abstract]

Schedule of Net Periodic Benefit Costs

The following table presents the components of MGE Energy's and MGE's net periodic benefit costs recognized for the three and nine months ended September 30, 2013 and 2012. 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)		2013		2012		2013		2012
Pension Benefits
Components of net periodic benefit cost:
Service cost	$	1,924	$	1,871	$	5,764	$	5,613
Interest cost		3,178		3,236		9,521		9,711
Expected return on assets		(4,764)		(3,917)		(14,273)		(11,756)
Amortization of:
Prior service cost		79		111		237		333
Actuarial loss		2,011		2,058		6,023		6,177
Net periodic benefit cost	$	2,428	$	3,359	$	7,272	$	10,078
Postretirement Benefits
Components of net periodic benefit cost:
Service cost	$	594	$	626	$	1,781	$	1,879
Interest cost		966		1,089		2,898		3,267
Expected return on assets		(542)		(421)		(1,626)		(1,263)
Amortization of:
Transition obligation		0		103		2		309
Prior service cost		28		27		83		81
Actuarial loss		310		601		930		1,802
Net periodic benefit cost	$	1,356	$	2,025	$	4,068	$	6,075