Pension And Other Postretirement Benefit Plans (Tables)

3 Months Ended

Jun. 30, 2012

Pension And Other Postretirement Benefit Plans [Abstract]

Components Of Company's Net Periodic Benefit Cost

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended June 30,						Three Months Ended June 30,
(in thousands of dollars)	2012			2011			2012			2011
Service cost	$	1,224		$	1,290		$	148		$	189
Interest cost	3,166			3,451			576			578
Expected return on plan assets	(3,497		)	(3,709		)	(31		)	(34		)
Net amortization and deferral	2,518			1,342			52			(58		)
Net periodic benefit cost	$	3,411		$	2,374		$	745		$	675