Supplemental Guarantor Information - Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
Consolidating Statement of Operations
Revenues	$ 4,906.3			$ 4,435.3			$ 12,554.0	$ 11,562.9
Cost of sales	3,831.6			3,397.2			9,839.4	8,939.0
Selling, general and administrative expense	480.0			434.9			1,327.0	1,219.9
Gain on sale of assets	(22.6)			0.0			(53.9)	(14.5)
Other (income) expense	(9.4)			(13.0)			(23.7)	(33.8)
Income before income taxes	626.7			616.2			1,465.2	1,452.3
Income tax expense	153.1			162.5			350.5	458.9
Equity in net income of subsidiaries, net of tax	0.0			0.0			0.0	0.0
Net income	473.6	$ 354.4	$ 286.7	453.7	$ 350.8	$ 188.8	1,114.7	993.4
Net income (loss) attributable to noncontrolling interests	(1.2)			(0.1)			1.5	(0.7)
Net Income (Loss) Attributable to Parent	474.8			453.8			1,113.2	994.1
Eliminations [Member]
Consolidating Statement of Operations
Revenues	(73.1)			(8.9)			(141.8)	(22.4)
Cost of sales	(67.3)			(5.6)			(127.8)	(16.5)
Selling, general and administrative expense	0.0			0.0			0.0	0.0
Gain on sale of assets	0.0						(2.5)	0.0
Other (income) expense	0.0			0.0			0.0	0.0
Income before income taxes	(5.8)			(3.3)			(11.5)	(5.9)
Income tax expense	(1.5)			0.0			(2.8)	(1.0)
Equity in net income of subsidiaries, net of tax	(314.6)			(336.2)			(764.2)	(747.5)
Net income	(318.9)			(339.5)			(772.9)	(752.4)
Net income (loss) attributable to noncontrolling interests	0.7			3.4			3.4	3.4
Net Income (Loss) Attributable to Parent	(319.6)			(342.9)			(776.3)	(755.8)
D.R. Horton, Inc. [Member]
Consolidating Statement of Operations
Revenues	1,939.3			1,630.8			4,850.2	4,082.7
Cost of sales	1,529.6			1,293.3			3,836.6	3,235.0
Selling, general and administrative expense	191.8			174.4			543.3	483.4
Gain on sale of assets	0.0						(2.0)	0.0
Other (income) expense	(0.9)			(1.5)			(2.9)	(3.5)
Income before income taxes	218.8			164.6			475.2	367.8
Income tax expense	53.7			43.8			114.2	117.0
Equity in net income of subsidiaries, net of tax	314.6			336.2			764.2	747.5
Net income	479.7			457.0			1,125.2	998.3
Net income (loss) attributable to noncontrolling interests	0.0			0.0			0.0	0.0
Net Income (Loss) Attributable to Parent	479.7			457.0			1,125.2	998.3
Guarantor Subsidiaries [Member]
Consolidating Statement of Operations
Revenues	2,820.9			2,693.9			7,322.3	7,149.0
Cost of sales	2,286.9			2,092.5			5,957.8	5,659.4
Selling, general and administrative expense	193.4			174.1			523.9	490.6
Gain on sale of assets	(0.2)						(0.2)	0.0
Other (income) expense	(0.5)			0.5			(1.3)	(0.2)
Income before income taxes	341.3			426.8			842.1	999.2
Income tax expense	84.1			113.6			202.3	318.7
Equity in net income of subsidiaries, net of tax	0.0			0.0			0.0	0.0
Net income	257.2			313.2			639.8	680.5
Net income (loss) attributable to noncontrolling interests	0.0			0.0			0.0	0.0
Net Income (Loss) Attributable to Parent	257.2			313.2			639.8	680.5
Non-Guarantor Subsidiaries [Member]
Consolidating Statement of Operations
Revenues	219.2			119.5			523.3	353.6
Cost of sales	82.4			17.0			172.8	61.1
Selling, general and administrative expense	94.8			86.4			259.8	245.9
Gain on sale of assets	(22.4)						(49.2)	(14.5)
Other (income) expense	(8.0)			(12.0)			(19.5)	(30.1)
Income before income taxes	72.4			28.1			159.4	91.2
Income tax expense	16.8			5.1			36.8	24.2
Equity in net income of subsidiaries, net of tax	0.0			0.0			0.0	0.0
Net income	55.6			23.0			122.6	67.0
Net income (loss) attributable to noncontrolling interests	(1.9)			(3.5)			(1.9)	(4.1)
Net Income (Loss) Attributable to Parent	$ 57.5			$ 26.5			$ 124.5	$ 71.1