Pension and Other Postretirement Plans (Tables)

3 Months Ended

Mar. 31, 2015

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 months endedMarch 31,2015 and 2014. A portion of the net periodic benefit cost is capitalized within the consolidated balance sheets.

		Three Months Ended
		March 31,
(In thousands)		2015		2014
Pension Benefits
Components of net periodic cost (benefit):
Service cost	$	1,798	$	1,484
Interest cost		3,440		3,251
Expected return on assets		(5,677)		(5,279)
Amortization of:
Prior service cost		6		49
Actuarial loss		1,334		173
Net periodic cost (benefit)	$	901	$	(322)
Postretirement Benefits
Components of net periodic cost (benefit):
Service cost	$	383	$	330
Interest cost		778		772
Expected return on assets		(703)		(654)
Amortization of:
Transition obligation		1		1
Prior service benefit		(667)		(668)
Actuarial loss		262		39
Net periodic cost (benefit)	$	54	$	(180)