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Average annual operating profit earned period, maximum.

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Average annual operating profit earned period minimum.

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Debt instrument, revolving and term loan

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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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Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

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-Topic 360

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Jan. 09, 2012	Dec. 31, 2014 Segment	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Line Items]
Number of reportable segments		4us-gaap_NumberOfReportableSegments
Loss on sale of Axiom Re		$ 47,425,000us-gaap_GainLossOnDispositionOfAssets1
Average annual operating profit earned period, minimum (years)		1 year	1 year	1 year
Average annual operating profit earned period, maximum (years)		3 years	3 years	3 years
Fair value of long term debt		650,000,000us-gaap_LongTermDebtFairValue	650,000,000us-gaap_LongTermDebtFairValue
Short-term notes carrying value		25,000,000us-gaap_ShortTermBorrowings
Revolving and term loan	50,000,000bro_DebtInstrumentRevolvingAndTermLoan
Non-compete agreements [Member]
Accounting Policies [Line Items]
Estimated lives of amortizable intangible assets		6 years 9 months 18 days	7 years
Minimum [Member]
Accounting Policies [Line Items]
Estimated useful lives of the related assets		3 years
Minimum [Member] \| Non-compete agreements [Member]
Accounting Policies [Line Items]
Estimated lives of amortizable intangible assets		5 years
Maximum [Member]
Accounting Policies [Line Items]
Estimated useful lives of the related assets		15 years
Maximum [Member] \| Non-compete agreements [Member]
Accounting Policies [Line Items]
Estimated lives of amortizable intangible assets		15 years
J P Morgan Credit Facility [Member]
Accounting Policies [Line Items]
Revolving and term loan		$ 550,000,000