Commitments, Contingencies and Off-Balance Sheet Arrangements - Contractual Obligations (Detail) $ in Millions	Mar. 31, 2021 USD ($)
Note Purchase Agreements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2022	$ 200.0
Contractual Obligations, Payments Due by Period, 2023	250.0
Contractual Obligations, Payments Due by Period, 2024	475.0
Contractual Obligations, Payments Due by Period, 2025	200.0
Contractual Obligations, Payments Due by Period, Thereafter	3,248.0
Contractual Obligations, Payments Due by Period, Total	4,373.0
Premium Financing Debt Facility [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2021	151.3
Contractual Obligations, Payments Due by Period, Total	151.3
Interest On Debt [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2021	188.7
Contractual Obligations, Payments Due by Period, 2022	186.0
Contractual Obligations, Payments Due by Period, 2023	177.2
Contractual Obligations, Payments Due by Period, 2024	160.4
Contractual Obligations, Payments Due by Period, 2025	145.8
Contractual Obligations, Payments Due by Period, Thereafter	628.9
Contractual Obligations, Payments Due by Period, Total	1,487.0
Total Debt Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2021	340.0
Contractual Obligations, Payments Due by Period, 2022	386.0
Contractual Obligations, Payments Due by Period, 2023	427.2
Contractual Obligations, Payments Due by Period, 2024	635.4
Contractual Obligations, Payments Due by Period, 2025	345.8
Contractual Obligations, Payments Due by Period, Thereafter	3,876.9
Contractual Obligations, Payments Due by Period, Total	6,011.3
Operating Lease Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2021	83.8
Contractual Obligations, Payments Due by Period, 2022	98.4
Contractual Obligations, Payments Due by Period, 2023	78.4
Contractual Obligations, Payments Due by Period, 2024	57.3
Contractual Obligations, Payments Due by Period, 2025	43.4
Contractual Obligations, Payments Due by Period, Thereafter	82.8
Contractual Obligations, Payments Due by Period, Total	444.1
Less Sublease Arrangements [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Receivable by Period, 2021	(0.3)
Contractual Obligations, Payments Receivable by Period, 2022	(0.3)
Contractual Obligations, Payments Receivable by Period, 2023	(0.3)
Contractual Obligations, Payments Receivable by Period, 2024	(0.2)
Contractual Obligations, Payments Receivable by Period, 2025	(0.2)
Contractual Obligations, Payments Receivable by Period, Thereafter	(0.5)
Contractual Obligations, Payments Receivable by Period, Total	(1.8)
Outstanding Purchase Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2021	65.9
Contractual Obligations, Payments Due by Period, 2022	55.4
Contractual Obligations, Payments Due by Period, 2023	36.6
Contractual Obligations, Payments Due by Period, 2024	25.4
Contractual Obligations, Payments Due by Period, 2025	20.4
Contractual Obligations, Payments Due by Period, Thereafter	28.8
Contractual Obligations, Payments Due by Period, Total	232.5
Total Contractual Obligations [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Contractual Obligations, Payments Due by Period, 2021	489.4
Contractual Obligations, Payments Due by Period, 2022	539.5
Contractual Obligations, Payments Due by Period, 2023	541.9
Contractual Obligations, Payments Due by Period, 2024	717.9
Contractual Obligations, Payments Due by Period, 2025	409.4
Contractual Obligations, Payments Due by Period, Thereafter	3,988.0
Contractual Obligations, Payments Due by Period, Total	$ 6,686.1

Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]

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- Definition

Recorded unconditional purchase obligation due after fourth year.

+ References

No definition available.

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- Definition

Recorded unconditional purchase obligation receivable.

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Recorded unconditional purchase obligation receivable after fifth year.

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- Definition

Recorded unconditional purchase obligation receivable in fifth year.

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Recorded unconditional purchase obligation receivable in fourth year.

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- Definition

Recorded unconditional purchase obligation receivable in second year.

+ References

No definition available.

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- Definition

Recorded unconditional purchase obligation receivable in third year.

+ References

No definition available.

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- Definition

Recorded unconditional purchase obligation receivable within one year.

+ References

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121559207&loc=d3e25383-109308

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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 remainder of current fiscal year.

+ References

No definition available.

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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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