Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenues	$ 6,446.9	$ 4,500.0	$ 12,380.3	$ 8,520.7
Cost of sales	4,650.9	3,450.8	8,983.5	6,535.0
Selling, general and administrative expense	621.5	466.8	1,207.4	922.6
Gain on sale of assets	0.0	(28.5)	(14.0)	(59.5)
Other (income) expense	(5.4)	(10.4)	(10.8)	(21.9)
Income before income taxes	1,179.9	621.3	2,214.2	1,144.5
Income tax expense	246.0	137.3	485.1	228.1
Net income	933.9	484.0	1,729.1	916.4
Net income (loss) attributable to noncontrolling interests	4.4	1.3	7.8	2.4
Net income attributable to D.R. Horton, Inc.	$ 929.5	$ 482.7	$ 1,721.3	$ 914.0
Basic net income per common share attributable to D.R. Horton, Inc. (in dollars per share)	$ 2.57	$ 1.32	$ 4.74	$ 2.49
Weighted average number of common shares	362.3	365.8	363.4	367.1
Diluted net income per common share attributable to D.R. Horton, Inc. (in dollars per share)	$ 2.53	$ 1.30	$ 4.67	$ 2.46
Adjusted weighted average number of common shares	367.2	370.1	368.6	371.8