Employee Savings Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Savings Plan [Abstract]
Compensation and Employee Benefit Plans [Text Block]	Employee Savings PlanThe Company has an Employee Savings Plan (401(k)) in which substantially all employees with more than 30 days of service are eligible to participate. Under this plan, Brown & Brown makes matching contributions of up to 4.0% of each participant’s annual compensation. Prior to 2014, the Company’s matching contribution was up to 2.5% of each participant’s annual compensation with an additional discretionary profit-sharing contribution each year, which equaled 1.5% of each eligible employee’s compensation. The Company’s contributions to the plan totaled $19.6 million in 2017, $19.3 million in 2016 and $17.8 million in 2015.
Service Period Eligible to Participate for Employee Savings Plan	$ 30
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	4.00%		2.50%
Discretionary Profit Sharing Contribution Percentage of Employees Salary	1.50%
Defined Benefit Plan, Contributions by Employer	$ 19,600,000	$ 19,300,000	$ 17,800,000