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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- Definition

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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- Definition

Expiration lists

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- Definition

Fair Value Inputs, Attrition Rate

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- Definition

Goodwill Related to Nondeductible Amortizable Intangible Assets

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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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- Definition

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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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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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- Definition

Amount of deferred tax liability attributable to taxable temporary differences.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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Percentage of assumed long-term growth in revenues, used as an input to measure fair value.

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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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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		186 Months Ended
Business Combinations - Additional Information (Detail)	Jun. 30, 2017 USD ($) Entity	Jun. 30, 2016 USD ($) Entity	Jun. 30, 2017 USD ($) Entity	Jun. 30, 2016 USD ($) Entity	Jun. 30, 2017 USD ($) Entity
Business Acquisition [Line Items]
Accretion of the discount on acquisition	$ 5,200,000	$ 4,000,000	$ 10,300,000	$ 8,200,000
Number of companies acquired \| Entity	46	27	65	57	443
Aggregate amount of maximum earnout obligations related to acquisitions			$ 564,100,000
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet			267,900,000
Income (expense) related to net adjustments to estimated fair value of liability for earnout obligations	$ 100,000	$ (9,200,000)	(6,600,000)	$ (8,900,000)
Goodwill	154,400,000		154,400,000		$ 154,400,000
Expiration lists	148,700,000		148,700,000		148,700,000
Non-compete agreements	2,900,000		2,900,000		2,900,000
Total revenues related to acquisitions in the aggregate	1,566,700,000	$ 1,453,700,000	2,991,200,000	$ 2,781,500,000
Brokerage and Risk Management [Member]
Business Acquisition [Line Items]
Goodwill	154,400,000		154,400,000		154,400,000
Expiration lists	148,700,000		148,700,000		148,700,000
Non-compete agreements	2,900,000		$ 2,900,000		2,900,000
Expiration Lists [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			3 years
Expiration Lists [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			15 years
Non-Compete Agreements [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			3 years
Non-Compete Agreements [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			5 years
Trade Names [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			3 years
Trade Names [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Estimated useful lives of intangibles assets, years			5 years
2017 Acquisitions [Member] \| Market Approach Valuation Technique [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Revenue growth rate			4.00%
Discount rate			8.50%
2017 Acquisitions [Member] \| Market Approach Valuation Technique [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Revenue growth rate			17.00%
Discount rate			9.00%
2017 Acquisitions [Member] \| Income Approach Valuation Technique [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Revenue growth rate			3.00%
Discount rate			12.00%
Attrition rate			5.00%
2017 Acquisitions [Member] \| Income Approach Valuation Technique [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Revenue growth rate			3.30%
Discount rate			14.00%
Attrition rate			8.00%
2016 Acquisitions [Member] \| Income Approach Valuation Technique [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Revenue growth rate			3.00%
Discount rate			12.00%
Attrition rate			5.00%
2016 Acquisitions [Member] \| Income Approach Valuation Technique [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Revenue growth rate			3.30%
Discount rate			14.00%
Attrition rate			8.00%
Business Acquisition [Member]
Business Acquisition [Line Items]
Annualized revenue of business acquisitions			$ 105,000,000
Total revenues related to acquisitions in the aggregate			37,500,000
Net earnings			1,300,000
Business Acquisition [Member] \| Brokerage [Member]
Business Acquisition [Line Items]
Expiration lists	148,700,000		148,700,000		148,700,000
Non-compete agreements	2,900,000		2,900,000		2,900,000
Deferred tax liability	7,600,000		7,600,000		7,600,000
Goodwill related to nondeductible amortizable intangible assets			7,600,000
Business Acquisition [Member] \| Expiration Lists [Member] \| Brokerage [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes	23,200,000		23,200,000		23,200,000
Business Acquisition [Member] \| Non-Compete Agreements [Member] \| Brokerage [Member]
Business Acquisition [Line Items]
Business acquisition not deductible for income tax purposes	$ 1,400,000		$ 1,400,000		$ 1,400,000