Pension and Other Postretirement Benefit Plans (Tables)

6 Months Ended

Jun. 30, 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 June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(In thousands)
Defined Benefit Pension Plans
Service cost	$	277		$	273		$	554		$	545
Interest cost	1,358			1,332			2,716			2,664
Expected return on plan assets	(2,140		)	(2,161		)	(4,281		)	(4,322		)
Amortization of prior service credit	—			(1		)	—			(2		)
Amortization of unrecognized net loss	572			1,056			1,144			2,112
Net periodic benefit cost	$	67		$	499		$	133		$	997
Postretirement Benefit Plan
Service cost	$	2		$	4		$	4		$	8
Interest cost	33			33			66			67
Amortization of prior service cost	29			32			58			65
Amortization of unrecognized net gain	(25		)	—			(49		)	(1		)
Net periodic benefit cost	$	39		$	69		$	79		$	139