Accrued Expenses and Other Liabilities - Summary of Accrued Expenses and Other Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Other Liabilities Disclosure [Abstract]
Accrued bonuses	$ 76,891us-gaap_AccruedBonusesCurrent	$ 70,272us-gaap_AccruedBonusesCurrent
Accrued compensation and benefits	36,241us-gaap_AccruedEmployeeBenefitsCurrent	35,145us-gaap_AccruedEmployeeBenefitsCurrent
Accrued rent and vendor expenses	29,039bro_AccruedRentAndVendorExpenses	19,235bro_AccruedRentAndVendorExpenses
Reserve for policy cancellations	9,074bro_ReserveForPolicyCancellations	8,010bro_ReserveForPolicyCancellations
Accrued interest	6,527us-gaap_InterestPayableCurrent	3,324us-gaap_InterestPayableCurrent
Other	23,384us-gaap_OtherAccruedLiabilitiesCurrent	21,414us-gaap_OtherAccruedLiabilitiesCurrent
Total	$ 181,156us-gaap_AccruedLiabilitiesCurrent	$ 157,400us-gaap_AccruedLiabilitiesCurrent

Carrying value as of the balance sheet date of obligations incurred and payable for incentive compensation awarded to employees and directors or earned by them based on the terms of one or more relevant arrangements. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of obligations, excluding pension and other postretirement benefits, incurred through that date and payable for perquisites provided to employees pertaining to services received from them. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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