Debt - Narrative (Details)		3 Months Ended
	Oct. 10, 2023 USD ($)	Dec. 31, 2023 USD ($) creditFacility	Dec. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)
Line Of Credit Facility [Line Items]
Proceeds from issuance of long-term debt		$ 898,275,000	$ 797,258,000
Maximum debt-to-total-capitalization ratio		70.00%
Debt-to-total-capitalization ratio		0.41
Minimum
Line Of Credit Facility [Line Items]
Outstanding indebtedness		$ 15,000,000
Maximum
Line Of Credit Facility [Line Items]
Outstanding indebtedness		100,000,000
Unsecured Senior Notes Due October 2053 | Senior Notes
Line Of Credit Facility [Line Items]
Debt face amount	$ 500,000,000
Interest rate	6.20%
Effective rate	5.56%
Unsecured Senior Notes Due October 2033 | Senior Notes
Line Of Credit Facility [Line Items]
Debt face amount	$ 400,000,000
Interest rate	5.90%
Effective rate	4.35%
Unsecured Senior Notes Due October 2033 and Unsecured Senior Notes Due October 2053 | Senior Notes
Line Of Credit Facility [Line Items]
Proceeds from issuance of long-term debt	$ 889,400,000
Five Year Unsecured Revolving Credit Agreement
Line Of Credit Facility [Line Items]
Outstanding commercial paper		$ 0		$ 241,900,000
Five Year Unsecured Revolving Credit Agreement | Minimum | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread		0.00%
Five Year Unsecured Revolving Credit Agreement | Minimum | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread		0.75%
Five Year Unsecured Revolving Credit Agreement | Maximum | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread		0.25%
Five Year Unsecured Revolving Credit Agreement | Maximum | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread		1.25%
Five Year Unsecured Revolving Credit Agreement | Commercial Paper
Line Of Credit Facility [Line Items]
Maximum borrowing capacity		$ 1,500,000,000
Debt agreement term		5 years
Accordion feature		$ 250,000,000
Maximum borrowing capacity post accordion feature		1,750,000,000
Five Year Unsecured Revolving Credit Agreement | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity		$ 2,500,000,000
Number of credit facilities | creditFacility		4
$900 Million Revolving Credit Facility | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity		$ 900,000,000
Debt agreement term		3 years
Accordion feature		$ 100,000,000
Maximum borrowing capacity post accordion feature		1,000,000,000
Outstanding borrowings		$ 0		0
$900 Million Revolving Credit Facility | Revolving Credit Facility | Minimum | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread		0.00%
$900 Million Revolving Credit Facility | Revolving Credit Facility | Minimum | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread		0.75%
$900 Million Revolving Credit Facility | Revolving Credit Facility | Maximum | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread		0.25%
$900 Million Revolving Credit Facility | Revolving Credit Facility | Maximum | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread		1.25%
$50 Million Bank Loan Agreement | Line of Credit
Line Of Credit Facility [Line Items]
Maximum borrowing capacity		$ 50,000,000
Debt agreement term		364 days
Outstanding borrowings		$ 0		$ 0
$50 Million Revolving Credit Facility
Line Of Credit Facility [Line Items]
Outstanding borrowings		0
$50 Million Revolving Credit Facility | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity		$ 50,000,000
Debt agreement term		364 days
Remaining borrowing capacity		$ 44,400,000