Commitments, Contingencies and Off-Balance Sheet Arrangements - Contractual Obligations (Detail) $ in Millions	Sep. 30, 2024 USD ($)
Senior Notes [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, Thereafter	$ 4,550.0
Contractual Obligations, Payments Due by Period, Total	4,550.0
Note Purchase Agreements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	200.0
Contractual Obligations, Payments Due by Period, 2026	640.0
Contractual Obligations, Payments Due by Period, 2027	478.0
Contractual Obligations, Payments Due by Period, 2028	200.0
Contractual Obligations, Payments Due by Period, Thereafter	2,005.0
Contractual Obligations, Payments Due by Period, Total	3,523.0
Premium Financing Debt Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2024	259.9
Contractual Obligations, Payments Due by Period, Total	259.9
Interest On Debt [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2024	56.1
Contractual Obligations, Payments Due by Period, 2025	374.0
Contractual Obligations, Payments Due by Period, 2026	355.0
Contractual Obligations, Payments Due by Period, 2027	336.7
Contractual Obligations, Payments Due by Period, 2028	317.2
Contractual Obligations, Payments Due by Period, Thereafter	4,285.8
Contractual Obligations, Payments Due by Period, Total	5,724.8
Total Debt Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2024	316.0
Contractual Obligations, Payments Due by Period, 2025	574.0
Contractual Obligations, Payments Due by Period, 2026	995.0
Contractual Obligations, Payments Due by Period, 2027	814.7
Contractual Obligations, Payments Due by Period, 2028	517.2
Contractual Obligations, Payments Due by Period, Thereafter	10,840.8
Contractual Obligations, Payments Due by Period, Total	14,057.7
Operating Lease Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Receivable by Period, 2024	(23.1)
Contractual Obligations, Payments Receivable by Period, 2025	(115.8)
Contractual Obligations, Payments Receivable by Period, 2026	(96.4)
Contractual Obligations, Payments Receivable by Period, 2027	(77.8)
Contractual Obligations, Payments Receivable by Period, 2028	(58.3)
Contractual Obligations, Payments Receivable by Period, Thereafter	(96.6)
Contractual Obligations, Payments Receivable by Period, Total	(468.0)
Less Sublease Arrangements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Receivable by Period, 2024	0.6
Contractual Obligations, Payments Receivable by Period, 2025	1.8
Contractual Obligations, Payments Receivable by Period, 2026	1.7
Contractual Obligations, Payments Receivable by Period, 2027	1.6
Contractual Obligations, Payments Receivable by Period, 2028	1.1
Contractual Obligations, Payments Receivable by Period, Thereafter	0.8
Contractual Obligations, Payments Receivable by Period, Total	7.6
Outstanding Purchase Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Receivable by Period, 2024	(31.5)
Contractual Obligations, Payments Receivable by Period, 2025	(87.5)
Contractual Obligations, Payments Receivable by Period, 2026	(49.6)
Contractual Obligations, Payments Receivable by Period, 2027	(37.8)
Contractual Obligations, Payments Receivable by Period, 2028	(22.2)
Contractual Obligations, Payments Receivable by Period, Thereafter	(65.2)
Contractual Obligations, Payments Receivable by Period, Total	(293.8)
Total Contractual Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2024	370.0
Contractual Obligations, Payments Due by Period, 2025	775.5
Contractual Obligations, Payments Due by Period, 2026	1,139.3
Contractual Obligations, Payments Due by Period, 2027	928.7
Contractual Obligations, Payments Due by Period, 2028	596.6
Contractual Obligations, Payments Due by Period, Thereafter	11,001.8
Contractual Obligations, Payments Due by Period, Total	$ 14,811.9

Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]

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Recorded unconditional purchase obligation receivable.

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Recorded unconditional purchase obligation receivable after fifth year.

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Recorded unconditional purchase obligation receivable in fifth year.

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Recorded unconditional purchase obligation receivable in fourth year.

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Recorded unconditional purchase obligation receivable in second year.

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Recorded unconditional purchase obligation receivable in third year.

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- Definition

Recorded unconditional purchase obligation receivable within one year.

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No definition available.

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- Definition

Amount of the recorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 440
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482648/440-10-50-6

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- Definition

Amount of recorded unconditional purchase obligation maturing after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 440
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482648/440-10-50-6

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- Definition

Amount of recorded unconditional purchase obligation to be paid in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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- Definition

Amount of recorded unconditional purchase obligation to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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- Definition

Amount of recorded unconditional purchase obligation to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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- Definition

Amount of recorded unconditional purchase obligation to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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- Definition

Amount of recorded unconditional purchase obligation to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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