Pension and Other Postretirement Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan

The components of net periodic benefit cost for the Corporation’s qualified and nonqualified pension plans and nonqualified postretirement benefit plan are as follows:

	Three Months Ended March 31,
	2016			2015
	(In thousands)
Defined Benefit Pension Plans
Service cost	$	277		$	273
Interest cost	1,358			1,332
Expected return on plan assets	(2,141		)	(2,161		)
Amortization of prior service credit	—			(1		)
Amortization of unrecognized net loss	572			1,056
Net periodic benefit cost	$	66		$	499
Postretirement Benefit Plan
Service cost	$	2		$	4
Interest cost	33			33
Amortization of prior service cost	29			32
Amortization of unrecognized net gain	(24		)	—
Net periodic benefit cost	$	40		$	69