Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Debt Instrument [Line Items]
Long-term debt	$ 8,435,000	$ 7,785,000
Finance lease obligations	48,075	48,890
Total long-term debt	8,483,075	7,833,890
Less:
Original issue premium on unsecured senior notes and debentures	(3,825)	(9,071)
Debt issuance cost	61,463	57,664
Current maturities of long-term debt	11,712	1,651
Total long-term debt, net	$ 8,413,725	7,783,646
Unsecured 3.00% Senior Notes, due June 2027
Debt Instrument [Line Items]
Interest rate	3.00%
Long-term debt	$ 500,000	500,000
Unsecured 2.625% Senior Notes, due September 2029
Debt Instrument [Line Items]
Interest rate	2.625%
Long-term debt	$ 500,000	500,000
Unsecured 1.50% Senior Notes, due January 2031
Debt Instrument [Line Items]
Interest rate	1.50%
Long-term debt	$ 600,000	600,000
Unsecured 5.45% Senior Notes, due October 2032
Debt Instrument [Line Items]
Interest rate	5.45%
Long-term debt	$ 300,000	300,000
Unsecured 5.90% Senior Notes, due November 2033
Debt Instrument [Line Items]
Interest rate	5.90%
Long-term debt	$ 725,000	725,000
Unsecured 5.95% Senior Notes, due October 2034
Debt Instrument [Line Items]
Interest rate	5.95%
Long-term debt	$ 200,000	200,000
Unsecured 5.50% Senior Notes, due June 2041
Debt Instrument [Line Items]
Interest rate	5.50%
Long-term debt	$ 400,000	400,000
Unsecured 4.15% Senior Notes, due January 2043
Debt Instrument [Line Items]
Interest rate	4.15%
Long-term debt	$ 500,000	500,000
Unsecured 4.125% Senior Notes, due October 2044
Debt Instrument [Line Items]
Interest rate	4.125%
Long-term debt	$ 750,000	750,000
Unsecured 4.30% Senior Notes, due October 2048
Debt Instrument [Line Items]
Interest rate	4.30%
Long-term debt	$ 600,000	600,000
Unsecured 4.125% Senior Notes, due March 2049
Debt Instrument [Line Items]
Interest rate	4.125%
Long-term debt	$ 450,000	450,000
Unsecured 3.375% Senior Notes, due September 2049
Debt Instrument [Line Items]
Interest rate	3.375%
Long-term debt	$ 500,000	500,000
Unsecured 2.85% Senior Notes, due February 2052
Debt Instrument [Line Items]
Interest rate	2.85%
Long-term debt	$ 600,000	600,000
Unsecured 5.75% Senior Notes, due October 2052
Debt Instrument [Line Items]
Interest rate	5.75%
Long-term debt	$ 500,000	500,000
Unsecured 6.20% Senior Notes, due November 2053
Debt Instrument [Line Items]
Interest rate	6.20%
Long-term debt	$ 500,000	500,000
Unsecured 5.00% Senior Notes, due December 2054
Debt Instrument [Line Items]
Interest rate	5.00%
Long-term debt	$ 650,000	0
Medium-term note Series A, 1995-1, 6.67%, due December 2025
Debt Instrument [Line Items]
Interest rate	6.67%
Long-term debt	$ 10,000	10,000
Unsecured 6.75% Debentures, due July 2028
Debt Instrument [Line Items]
Interest rate	6.75%
Long-term debt	$ 150,000	$ 150,000