Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 01, 2012	Jan. 02, 2011	Jan. 01, 2012	Jan. 02, 2011
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	$ 16,178	$ 17,476	$ 48,533	$ 52,428
Interest cost	37,321	37,717	111,963	113,151
Expected return on plan assets	(43,898)	(44,173)	(131,692)	(132,519)
Amortization of unrecognized net loss	23,983	21,362	71,950	64,086
Amortization of unrecognized prior service cost	(95)	(97)	(286)	(292)
Net periodic benefit (income) cost	33,489	32,285	100,468	96,854
Employer's contribution			61,600
Other Postretirement Benefits
Components of Net Periodic Benefit Cost
Service cost	19	22	57	176
Interest cost	1,953	2,130	5,860	6,689
Expected return on plan assets	(878)	(846)	(2,634)	(2,537)
Amortization of unrecognized net loss	744	819	2,230	2,264
Amortization of unrecognized prior service cost	(2,096)	(2,166)	(6,286)	(6,381)
Net periodic benefit (income) cost before curtailment gain	(258)	(41)	(773)	211
Curtailment gain				(448)
Net periodic benefit (income) cost	(258)	(41)	(773)	(237)
Employer's contribution			9,976
Additional employer's contribution during the remainder of fiscal year	4,048		4,048
Supplemental (nonqualified) executive retirement plan
Components of Net Periodic Benefit Cost
Employer's contribution			1,888
Additional employer's contribution during the remainder of fiscal year	$ 3,128		$ 3,128