QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018
Net sales:
Net sales	$ 426,178	$ 386,410	$ 468,146	$ 506,275	$ 541,529	$ 532,324	$ 515,648	$ 466,146	$ 1,787,009	$ 2,055,647	$ 1,777,721
Gross profit:
Gross profit	161,707	143,483	178,890	198,047	209,385	212,831	209,387	182,237
Net income from consolidated operations:
Net income from consolidated operations	67,580	57,564	80,909	129,802	92,573	89,059	90,083	88,026	335,855	359,741	285,686
Net income attributable to HEICO:
Net income attributable to HEICO	$ 62,327	$ 54,316	$ 75,453	$ 121,888	$ 85,684	$ 81,098	$ 81,782	$ 79,332	$ 313,984	$ 327,896	$ 259,233
Basic:
Basic (in dollars per share)	$ 0.46	$ 0.40	$ 0.56	$ 0.91	$ 0.64	$ 0.61	$ 0.61	$ 0.60	$ 2.33	$ 2.45	$ 1.96
Diluted:
Diluted (in dollars per share)	$ 0.45	$ 0.40	$ 0.55	$ 0.89	$ 0.62	$ 0.59	$ 0.60	$ 0.58	$ 2.29	$ 2.39	$ 1.90