Commitments, Contingencies and Off-Balance Sheet Arrangements - Contractual Obligations (Detail) $ in Millions	Mar. 31, 2025 USD ($)
Senior Notes [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2027	$ 750.0
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 [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, 2029	350.0
Contractual Obligations, Payments Due by Period, Thereafter	1,655.0
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, 2025	152.8
Contractual Obligations, Payments Due by Period, Total	152.8
Interest On Debt [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	433.8
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	9,295.4
Total Debt Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	786.6
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	22,521.2
Operating Lease Obligations [Member]
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	110.1
Contractual Obligations, Payments Due by Period, 2027	88.7
Contractual Obligations, Payments Due by Period, 2028	66.5
Contractual Obligations, Payments Due by Period, 2029	37.2
Contractual Obligations, Payments Due by Period, Thereafter	82.3
Contractual Obligations, Payments Due by Period, Total	472.5
Less Sublease Arrangements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Receivable by Period, 2025	(1.7)
Contractual Obligations, Payments Receivable by Period, 2026	(2.0)
Contractual Obligations, Payments Receivable by Period, 2027	(1.9)
Contractual Obligations, Payments Receivable by Period, 2028	(1.3)
Contractual Obligations, Payments Receivable by Period, 2029	(1.0)
Contractual Obligations, Payments Receivable by Period, Total	(7.9)
Outstanding Purchase Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	102.4
Contractual Obligations, Payments Due by Period, 2026	103.6
Contractual Obligations, Payments Due by Period, 2027	63.4
Contractual Obligations, Payments Due by Period, 2028	38.7
Contractual Obligations, Payments Due by Period, 2029	25.6
Contractual Obligations, Payments Due by Period, Thereafter	54.4
Contractual Obligations, Payments Due by Period, Total	388.1
Total Contractual Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2025	975.0
Contractual Obligations, Payments Due by Period, 2026	1,463.2
Contractual Obligations, Payments Due by Period, 2027	1,971.2
Contractual Obligations, Payments Due by Period, 2028	843.1
Contractual Obligations, Payments Due by Period, 2029	1,690.3
Contractual Obligations, Payments Due by Period, Thereafter	16,431.1
Contractual Obligations, Payments Due by Period, Total	$ 23,373.9

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 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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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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- 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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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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- 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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