Pension and Other Postretirement Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2012

Pension and Other Postretirement Benefit Plans [Abstract]

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2012			2011			2012			2011
	(In thousands)
Defined Benefit Pension Plans
Service cost	$	303		$	291		$	606		$	582
Interest cost		1,215			1,208			2,430			2,415
Expected return on plan assets		(1,732	)		(1,582	)		(3,463	)		(3,164	)
Amortization of prior service credit		(1	)		—			(1	)		(1	)
Amortization of unrecognized net loss		615			269			1,229			539
Net periodic benefit cost	$	400		$	186		$	801		$	371
Postretirement Benefit Plan
Interest cost	$	36		$	41		$	73		$	83
Amortization of prior service credit		(75	)		(81	)		(150	)		(162	)
Amortization of unrecognized net gain		(7	)		(8	)		(14	)		(16	)
Net periodic benefit income	$	(46	)	$	(48	)	$	(91	)	$	(95	)