Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share Reconciliation [Abstract]
Net Income (Loss) Attributable to Parent	$ 4,745.7	$ 5,857.5	$ 4,175.8
Denominator:
Denominator for basic earnings per share - weighted average common shares	340.7	351.7	361.1
Effect of dilutive securities:
Employee stock awards	2.6	3.1	4.7
Denominator for diluted earnings per share - adjusted weighted average common shares	343.3	354.8	365.8
Basic net income per common share attributable to D.R. Horton, Inc.	$ 13.93	$ 16.65	$ 11.56
Diluted net income per common share attributable to D.R. Horton, Inc.	$ 13.82	$ 16.51	$ 11.41