Pensions and Other Postretirement Benefits (Tables)

6 Months Ended

Oct. 26, 2011

Compensation and Retirement Disclosure [Abstract]

Components of net periodic benefit cost

	Second Quarter Ended
	October 26, 2011			October 27, 2010			October 26, 2011			October 27, 2010
	Pension Benefits						Other Retiree Benefits
	(Thousands of Dollars)
Service cost	$	8,445		$	8,096		$	1,489		$	1,567
Interest cost	34,939			35,512			2,860			3,162
Expected return on plan assets	(58,756		)	(57,278		)	—			—
Amortization of prior service cost/(credit)	495			617			(1,532		)	(1,291		)
Amortization of unrecognized loss	20,937			19,388			274			401
Net periodic benefit cost	$	6,060		$	6,335		$	3,091		$	3,839

	Six Months Ended
	October 26, 2011			October 27, 2010			October 26, 2011			October 27, 2010
	Pension Benefits						Other Retiree Benefits
	(Thousands of Dollars)
Service cost	$	17,056		$	15,833		$	2,997		$	3,128
Interest cost	70,486			69,791			5,747			6,316
Expected return on plan assets	(118,537		)	(112,570		)	—			—
Amortization of prior service cost/(credit)	993			1,208			(3,062		)	(2,581		)
Amortization of unrecognized loss	42,166			38,356			547			802
Net periodic benefit cost	$	12,164		$	12,618		$	6,229		$	7,665