Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Supplemental Cash Flow Elements [Abstract]
Effect of foreign exchange rate changes on cash and cash equivalents inclusive of fiduciary cash	$ 14.3	$ (0.3)

Effect of foreign exchange rate cash changes in cash and cash equivalents inclusive of fiduciary.

No definition available.

Name:	bro_EffectOfForeignExchangeRateCashChangesInCashAndCashEquivalentsInclusiveOfFiduciary
Namespace Prefix:	bro_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration