Credit Facilities, Short-term Borrowings and Long-term Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Oct. 01, 2018	Sep. 30, 2018
Debt Instrument [Line Items]
Long-term debt	$ 864,899		$ 1,092,397
Unamortized debt issuance costs	(2,478)		(2,895)
Less: Current portion of long-term debt
Long-term debt, less current portion	$ 864,899	$ 1,092,397	1,092,397
Series D Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	6.39%
Maturity date	Oct. 01, 2018
Long-term debt			100,000
Series F Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	8.24%
Maturity date	Apr. 03, 2019
Long-term debt			43,000
Series G Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	3.42%
Maturity date	Nov. 15, 2020
Long-term debt	$ 50,000		50,000
Series H Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.03%
Maturity date	Nov. 15, 2023
Long-term debt	$ 25,000		25,000
Series I Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.18%
Maturity date	Nov. 15, 2025
Long-term debt	$ 25,000		25,000
Series J Notes [Member]
Debt Instrument [Line Items]
Variable interest rate	3.37%
Series J Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Maturity date	Nov. 15, 2020
Long-term debt	$ 50,000		50,000
Series J Notes [Member] | Notes Payable to Banks [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Variable interest rate	1.25%
Series K Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.03%
Maturity date	Nov. 15, 2023
Long-term debt	$ 50,000		50,000
Series L Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.18%
Maturity date	Nov. 15, 2025
Long-term debt	$ 50,000		50,000
Series M Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	1.12%
Maturity date	Sep. 23, 2026
Long-term debt	$ 43,770		46,437
Series N Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	1.31%
Maturity date	Sep. 23, 2028
Long-term debt	$ 84,257		89,393
Series O Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	1.57%
Maturity date	Sep. 23, 2031
Long-term debt	$ 47,053		49,921
Series P Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.27%
Maturity date	May 30, 2025
Long-term debt	$ 85,000		85,000
Series R Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.41%
Maturity date	May 30, 2029
Long-term debt	$ 75,000		75,000
Series S Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.46%
Maturity date	May 30, 2030
Long-term debt	$ 75,000		75,000
Series T Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.61%
Maturity date	May 30, 2033
Long-term debt	$ 80,000		80,000
Series Q Notes [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest rate	4.35%
Maturity date	May 30, 2027
Long-term debt	$ 85,000		85,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date	Jun. 19, 2024
Long-term debt	$ 42,297		$ 116,541
Revolving Credit Facility [Member] | Minimum [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Variable interest rate	0.875%
Revolving Credit Facility [Member] | Maximum [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Variable interest rate	1.75%