Commitments, Contingencies and Off-Balance Sheet Arrangements - Contractual Obligations (Detail) $ in Millions	Sep. 30, 2025 USD ($)
Senior Notes
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	$ 0.0
Contractual Obligations, Payments Due by Period, 2026	0.0
Contractual Obligations, Payments Due by Period, 2027	750.0
Contractual Obligations, Payments Due by Period, 2028	0.0
Contractual Obligations, Payments Due by Period, 2029	750.0
Contractual Obligations, Payments Due by Period, Thereafter	8,050.0
Contractual Obligations, Payments Due by Period, Total	9,550.0
Note Purchase Agreements
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	0.0
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, 2029	350.0
Contractual Obligations, Payments Due by Period, Thereafter	1,655.0
Contractual Obligations, Payments Due by Period, Total	3,323.0
Credit Agreement
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	130.0
Contractual Obligations, Payments Due by Period, 2026	0.0
Contractual Obligations, Payments Due by Period, 2027	0.0
Contractual Obligations, Payments Due by Period, 2028	0.0
Contractual Obligations, Payments Due by Period, 2029	0.0
Contractual Obligations, Payments Due by Period, Thereafter	0.0
Contractual Obligations, Payments Due by Period, Total	130.0
Premium Financing Debt Facility
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	237.4
Contractual Obligations, Payments Due by Period, 2026	0.0
Contractual Obligations, Payments Due by Period, 2027	0.0
Contractual Obligations, Payments Due by Period, 2028	0.0
Contractual Obligations, Payments Due by Period, 2029	0.0
Contractual Obligations, Payments Due by Period, Thereafter	0.0
Contractual Obligations, Payments Due by Period, Total	237.4
Interest on debt
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	87.7
Contractual Obligations, Payments Due by Period, 2026	611.5
Contractual Obligations, Payments Due by Period, 2027	593.0
Contractual Obligations, Payments Due by Period, 2028	539.2
Contractual Obligations, Payments Due by Period, 2029	528.5
Contractual Obligations, Payments Due by Period, Thereafter	6,589.4
Contractual Obligations, Payments Due by Period, Total	8,949.3
Total debt obligations
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	455.1
Contractual Obligations, Payments Due by Period, 2026	1,251.5
Contractual Obligations, Payments Due by Period, 2027	1,821.0
Contractual Obligations, Payments Due by Period, 2028	739.2
Contractual Obligations, Payments Due by Period, 2029	1,628.5
Contractual Obligations, Payments Due by Period, Thereafter	16,294.4
Contractual Obligations, Payments Due by Period, Total	22,189.7
Operating lease obligations
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	70.3
Contractual Obligations, Payments Due by Period, 2026	170.9
Contractual Obligations, Payments Due by Period, 2027	139.3
Contractual Obligations, Payments Due by Period, 2028	101.5
Contractual Obligations, Payments Due by Period, 2029	76.5
Contractual Obligations, Payments Due by Period, Thereafter	224.6
Contractual Obligations, Payments Due by Period, Total	783.1
Less sublease arrangements
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, Thereafter	0.0
Contractual Obligations, Sublease Arrangement, 2025	(0.8)
Contractual Obligations, Sublease Arrangement, 2026	(2.7)
Contractual Obligations, Sublease Arrangement, 2027	(2.0)
Contractual Obligations, Sublease Arrangement, 2028	(1.4)
Contractual Obligations, Sublease Arrangement, 2029	(1.0)
Contractual Obligations, Sublease Arrangement, Total	(7.9)
Outstanding purchase obligations
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	67.7
Contractual Obligations, Payments Due by Period, 2026	237.7
Contractual Obligations, Payments Due by Period, 2027	203.4
Contractual Obligations, Payments Due by Period, 2028	62.0
Contractual Obligations, Payments Due by Period, 2029	41.4
Contractual Obligations, Payments Due by Period, Thereafter	57.2
Contractual Obligations, Payments Due by Period, Total	669.4
Total contractual obligations
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	592.3
Contractual Obligations, Payments Due by Period, 2026	1,657.4
Contractual Obligations, Payments Due by Period, 2027	2,161.7
Contractual Obligations, Payments Due by Period, 2028	901.3
Contractual Obligations, Payments Due by Period, 2029	1,745.4
Contractual Obligations, Payments Due by Period, Thereafter	16,576.2
Contractual Obligations, Payments Due by Period, Total	$ 23,634.3

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 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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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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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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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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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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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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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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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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