Debt and Credit Facility (Details 1) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Mar. 29, 2014	Apr. 01, 2017
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis			three-month London Interbank Offered Rate (LIBOR) plus 91.43 bps
Net interest rate received (paid) from interest rate swap	$ 1,500,000		$ 2,100,000
Long-term debt	$ 1,738,666,000		1,738,666,000			$ 995,247,000
Amortization of Debt Discount (Premium)			$ 1,964,000	$ 6,034,000
2.125% 2019 Senior Debentures [Member]
Debt Instrument [Line Items]
Discount Percent Of Par	99.477%		99.477%
Debt instrument, long term debt, remaining discount amortization period			1 year 5 months 15 days
Debt Instrument, Face Amount	$ 500,000,000		$ 500,000,000			500,000,000
Debt Instrument, Unamortized Discount	(770,000)		(770,000)			(1,037,000)
Unamortized Debt Issuance Expense	$ 484,000		$ 484,000			654,000
3.0% 2021 Senior Debentures [Member]
Debt Instrument [Line Items]
Discount Percent Of Par	99.281%		99.281%
Debt instrument, long term debt, remaining discount amortization period			3 years 5 months 15 days
Debt Instrument, Face Amount	$ 500,000,000		$ 500,000,000			500,000,000
Debt Instrument, Unamortized Discount	(1,852,000)		(1,852,000)			(2,107,000)
Unamortized Debt Issuance Expense	833,000		833,000			955,000
2019 and 2021 Notes Payable [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt					$ 990,100,000
Long-term debt	996,061,000		996,061,000			995,247,000
Interest Expense, Debt, Excluding Amortization	6,406,000	$ 6,406,000	12,813,000	12,813,000
Amortization of Debt Issuance Costs	146,000	146,000	293,000	293,000
Amortization of Debt Discount (Premium)	262,000	255,000	520,000	507,000
Interest Expense, Debt	$ 6,814,000	6,807,000	$ 13,626,000	13,613,000
Two Point and Nine Five Percent 2024 Senior Debentures [Member]
Debt Instrument [Line Items]
Discount Percent Of Par	99.887%		99.887%
Proceeds from Issuance of Long-term Debt			$ 745,200,000
Debt instrument, long term debt, remaining discount amortization period			6 years 8 months
Debt Instrument, Interest Rate, Stated Percentage	2.95%		2.95%
Debt Instrument, Face Amount	$ 750,000,000		$ 750,000,000			0
Debt Instrument, Unamortized Discount	(810,000)		(810,000)			0
Unamortized Debt Issuance Expense	(3,789,000)		(3,789,000)			0
Long Term Debt, Carrying Value before Hedging Adjustment	745,401,000		745,401,000			0
Fair Value Adjustment to Long-term Debt, Related to Interest Rate Swap	(2,796,000)		(2,796,000)
Derivative, Amount of Hedged Item						0
Long-term debt	742,605,000		742,605,000			$ 0
Interest Expense, Debt, Excluding Amortization	4,046,000	0	5,368,000	0
Amortization of Debt Issuance Costs	142,000	0	189,000	0
Amortization of Debt Discount (Premium)	27,000	0	37,000	0
Interest Expense, Debt	4,215,000	$ 0	$ 5,594,000	$ 0
two thousand and sixteen credit line [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Initiation Date			Dec. 07, 2016
Line of Credit Facility, Maximum Borrowing Capacity	400,000,000		$ 400,000,000
AdditionalborrowingcapacityfromRevolvingCreditFacility	150,000,000		$ 150,000,000
Line of Credit Facility, Expiration Date			Dec. 31, 2021
Line of Credit Facility, Average Outstanding Amount			$ 0
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	$ 2,800,000		$ 2,800,000