Business Acquisition Purchase Price Allocation Goodwill Not Expected Tax Deductible Amount

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- Definition

Business Acquisitions Purchase Price Allocation Goodwill Amount

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Business Combination ,Aggregate Earnout Obligation, Maximum

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Business Combination Aggregate Earnout Obligation Recorded Maximum

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Business Combination, Annualize Revenue

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Expiration lists

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Fair Value Inputs, Attrition Rate

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Value of input used to measure alternative investment.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Amount after tax of pro forma income from continuing operations as if the business combination had been completed at the beginning of a period.

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- Definition

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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For transactions that are recognized separately from the acquisition of assets and assumptions of liabilities in the business combination, such as related to pre-existing relationships with the acquiree, this element represents the disclosure of the amount of acquisition related costs which have been expensed.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Gross carrying amount before accumulated amortization as of the balance sheet date of payments made to third parties in exchange for their agreement not to engage in specified competitive practices in specified geographic territories for a specified period of time.

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Gross carrying amount before accumulated amortization as of the balance sheet date of the rights acquired through registration of a trade name to gain or protect exclusive use thereof for a reasonably expected period of economic benefit.

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The number of businesses acquired by the entity during the period.

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Business Combinations - Additional Information (Detail)	3 Months Ended		6 Months Ended		210 Months Ended
Business Combinations - Additional Information (Detail)	Jun. 30, 2019 USD ($) Entity	Jun. 30, 2018 USD ($) Entity	Jun. 30, 2019 USD ($) Entity	Jun. 30, 2018 USD ($) Entity	Jun. 30, 2019 USD ($) Entity
Business Acquisition [Line Items]
Accretion of the discount on acquisition	$ 5,800,000	$ 4,900,000	$ 11,400,000	$ 10,000,000.0
Number of companies acquired \| Entity	46	49	68	76	531
Aggregate amount of maximum earnout obligations related to acquisitions			$ 732,600,000
Income related to net adjustments to estimated fair value of liability for earnout obligations	$ 2,400,000	$ 10,900,000	5,100,000	$ 8,600,000
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet			393,400,000
Goodwill	604,300,000		604,300,000		$ 604,300,000
Expiration lists	374,600,000		374,600,000		374,600,000
Non-compete agreements	16,500,000		16,500,000		16,500,000
Trade names	2,300,000		$ 2,300,000		2,300,000
Estimated useful lives of intangibles assets, years			2 years
Total revenues related to acquisitions in the aggregate	1,672,100,000	$ 1,717,300,000	$ 3,696,300,000	$ 3,602,500,000
Brokerage and Risk Management [Member]
Business Acquisition [Line Items]
Goodwill	604,300,000		604,300,000		604,300,000
Expiration lists	374,600,000		374,600,000		374,600,000
Non-compete agreements	16,500,000		16,500,000		16,500,000
Trade names	$ 2,300,000		$ 2,300,000		$ 2,300,000
Minimum [Member] \| Expiration Lists [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			2 years
Minimum [Member] \| Non-Compete Agreements [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			3 years
Maximum [Member] \| Expiration Lists [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			15 years
Maximum [Member] \| Non-Compete Agreements [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			5 years
Maximum [Member] \| Trade Names [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			15 years
2018 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input	2.5		2.5		2.5
2018 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input	3.0		3.0		3.0
2018 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input	12.0		12.0		12.0
2018 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Long-term Revenue Growth Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input	12.5		12.5		12.5
2017 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Attrition rate			5.00%
2017 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Attrition rate			6.50%
Business Acquisition [Member]
Business Acquisition [Line Items]
Annualized revenue of business acquisitions			$ 265,700,000
Total revenues related to acquisitions in the aggregate			61,900,000
Net earnings			2,500,000
Business Acquisition [Member] \| Brokerage [Member]
Business Acquisition [Line Items]
Expiration lists	$ 374,600,000		374,600,000		$ 374,600,000
Non-compete agreements	16,500,000		16,500,000		16,500,000
Deferred tax liability	21,200,000		21,200,000		21,200,000
Business Acquisition [Member] \| Expiration Lists [Member] \| Brokerage [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes	95,700,000		95,700,000		95,700,000
Business Acquisition [Member] \| Non-Compete Agreements [Member] \| Brokerage [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes	12,300,000		12,300,000		12,300,000
Business Acquisition [Member] \| Trade Names [Member]
Business Acquisition [Line Items]
Trade names	$ 2,300,000		$ 2,300,000		$ 2,300,000
2019 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Discount Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input	3.0		3.0		3.0
2019 Acquisitions [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Discount Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input	20.0		20.0		20.0
2019 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Discount Rate [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Measurement input	7.5		7.5		7.5
2019 Acquisitions [Member] \| Valuation, Income Approach [Member] \| Measurement Input, Discount Rate [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Measurement input	8.2		8.2		8.2