Pension And Other Postretirement Benefit Plans (Tables)

9 Months Ended

Dec. 31, 2011

Pension And Other Postretirement Benefit Plans [Abstract]

Components Of Company's Net Periodic Benefit Cost

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended						Three Months Ended
	December 31,						December 31,
(in thousands of dollars)	2011			2010			2011			2010
Service cost	$	891		$	1,261		$	188		$	203
Interest cost		3,413			3,601			578			624
Expected return on plan assets		(3,700	)		(3,728	)		(33	)		(35	)
Net amortization and deferral		2,384			1,006			(58	)		(77	)
Net periodic benefit cost	$	2,988		$	2,140		$	675		$	715

	Pension Benefits						Other Postretirement Benefits
	Nine Months Ended						Nine Months Ended
	December 31,						December 31,
(in thousands of dollars)	2011			2010			2011			2010
Service cost	$	3,455		$	3,743		$	566		$	611
Interest cost		10,250			10,704			1,734			1,873
Expected return on plan assets		(11,055	)		(11,127	)		(101	)		(107	)
Net amortization and deferral		5,061			2,999			(175	)		(233	)
Net periodic benefit cost	$	7,711		$	6,319		$	2,024		$	2,144