Supplemental Guarantor Information - Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2019	Mar. 31, 2018
Consolidating Statement of Operations
Revenues	$ 4,128.7		$ 3,794.7		$ 7,647.7	$ 7,127.6
Cost of sales	3,256.7		2,961.6		6,007.8	5,541.8
Selling, general and administrative expense	444.2		400.9		847.0	785.1
Gain on sale of assets	(29.3)		(1.1)		(31.3)	(14.5)
Other (income) expense	(5.7)		(11.5)		(14.3)	(20.9)
Income before income taxes	462.8		444.8		838.5	836.1
Income tax expense	108.4		94.0		197.4	296.4
Equity in net income of subsidiaries, net of tax	0.0		0.0		0.0	0.0
Net income	354.4	$ 286.7	350.8	$ 188.8	641.1	539.7
Net income (loss) attributable to noncontrolling interests	3.1		(0.2)		2.7	(0.6)
Net Income (Loss) Attributable to Parent	351.3		351.0		638.4	540.3
Eliminations [Member]
Consolidating Statement of Operations
Revenues	(39.7)		(13.5)		(68.7)	(13.5)
Cost of sales	(35.0)		(10.9)		(60.5)	(10.9)
Selling, general and administrative expense	0.0		0.0		0.0	0.0
Gain on sale of assets	(2.5)		0.0		(2.5)	0.0
Other (income) expense	0.0		0.0		0.0	0.0
Income before income taxes	(2.2)		(2.6)		(5.7)	(2.6)
Income tax expense	(0.5)		0.0		(1.3)	0.0
Equity in net income of subsidiaries, net of tax	(253.5)		(267.5)		(449.4)	(410.8)
Net income	(255.2)		(270.1)		(453.8)	(413.4)
Net income (loss) attributable to noncontrolling interests	2.5		0.0		2.7	0.0
Net Income (Loss) Attributable to Parent	(257.7)		(270.1)		(456.5)	(413.4)
D.R. Horton, Inc. [Member]
Consolidating Statement of Operations
Revenues	1,575.2		1,288.0		2,910.9	2,451.9
Cost of sales	1,249.8		1,026.2		2,307.0	1,941.6
Selling, general and administrative expense	193.3		156.9		351.2	309.1
Gain on sale of assets	0.0		0.0		(2.0)	0.0
Other (income) expense	(1.1)		(1.7)		(2.0)	(2.1)
Income before income taxes	133.2		106.6		256.7	203.3
Income tax expense	31.4		20.7		60.6	71.8
Equity in net income of subsidiaries, net of tax	253.5		267.5		449.4	410.8
Net income	355.3		353.4		645.5	542.3
Net income (loss) attributable to noncontrolling interests	0.0		0.0		0.0	0.0
Net Income (Loss) Attributable to Parent	355.3		353.4		645.5	542.3
Guarantor Subsidiaries [Member]
Consolidating Statement of Operations
Revenues	2,419.7		2,402.7		4,501.4	4,455.1
Cost of sales	1,989.5		1,926.9		3,670.9	3,567.0
Selling, general and administrative expense	164.9		164.8		330.8	316.4
Gain on sale of assets	0.0		0.0		0.0	0.0
Other (income) expense	(0.4)		(0.7)		(0.8)	(0.7)
Income before income taxes	265.7		311.7		500.5	572.4
Income tax expense	62.3		67.4		118.1	205.3
Equity in net income of subsidiaries, net of tax	0.0		0.0		0.0	0.0
Net income	203.4		244.3		382.4	367.1
Net income (loss) attributable to noncontrolling interests	0.0		0.0		0.0	0.0
Net Income (Loss) Attributable to Parent	203.4		244.3		382.4	367.1
Non-Guarantor Subsidiaries [Member]
Consolidating Statement of Operations
Revenues	173.5		117.5		304.1	234.1
Cost of sales	52.4		19.4		90.4	44.1
Selling, general and administrative expense	86.0		79.2		165.0	159.6
Gain on sale of assets	(26.8)		(1.1)		(26.8)	(14.5)
Other (income) expense	(4.2)		(9.1)		(11.5)	(18.1)
Income before income taxes	66.1		29.1		87.0	63.0
Income tax expense	15.2		5.9		20.0	19.3
Equity in net income of subsidiaries, net of tax	0.0		0.0		0.0	0.0
Net income	50.9		23.2		67.0	43.7
Net income (loss) attributable to noncontrolling interests	0.6		(0.2)		0.0	(0.6)
Net Income (Loss) Attributable to Parent	$ 50.3		$ 23.4		$ 67.0	$ 44.3