Supplemental Guarantor Information - Consolidating Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 5,038.9	$ 4,906.3	$ 4,128.7	$ 3,519.0	$ 4,505.2	$ 4,435.3	$ 3,794.7	$ 3,332.7	$ 17,592.9	$ 16,068.0	$ 14,091.0
Unaudited Supplemental Consolidating Statement of Operations
Cost of sales									13,720.9	12,398.1	11,042.8
Selling, general and administrative expense									1,832.5	1,676.8	1,471.6
Equity in earnings of unconsolidated entities									(0.5)	(2.8)	0.0
Gain on sale of assets									(53.9)	(18.8)	0.0
Other (income) expense									(31.4)	(45.3)	(25.5)
Income before income taxes	660.1	626.7	462.8	375.7	607.7	616.2	444.8	391.2	2,125.3	2,060.0	1,602.1
Income tax expense (benefit)	156.2	153.1	108.4	89.0	138.8	162.5	94.0	202.4	506.7	597.7	563.7
Equity in net income of subsidiaries, net of tax									0.0	0.0	0.0
Net income	503.9	473.6	354.4	286.7	468.9	453.7	350.8	188.8	1,618.6	1,462.3	1,038.4
Net income attributable to noncontrolling interests	(1.4)	(1.2)	3.1	(0.5)	2.8	(0.1)	(0.2)	(0.5)	0.1	2.0	0.0
Net income attributable to D.R. Horton, Inc.	$ 505.3	$ 474.8	$ 351.3	$ 287.2	$ 466.1	$ 453.8	$ 351.0	$ 189.3	1,618.5	1,460.3	1,038.4
D.R Horton, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									6,812.6	5,835.0	4,773.6
Unaudited Supplemental Consolidating Statement of Operations
Cost of sales									5,350.3	4,612.5	3,827.6
Selling, general and administrative expense									731.3	665.6	584.3
Equity in earnings of unconsolidated entities									0.0	0.0
Gain on sale of assets									(2.0)	(2.4)
Other (income) expense									(5.0)	(6.0)	(8.3)
Income before income taxes									738.0	565.3	370.0
Income tax expense (benefit)									176.9	167.9	129.4
Equity in net income of subsidiaries, net of tax									1,084.0	1,069.7	798.2
Net income									1,645.1	1,467.1	1,038.8
Net income attributable to noncontrolling interests									0.0	0.0
Net income attributable to D.R. Horton, Inc.									1,645.1	1,467.1
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									10,210.4	9,795.7	8,939.5
Unaudited Supplemental Consolidating Statement of Operations
Cost of sales									8,301.5	7,752.5	7,199.6
Selling, general and administrative expense									744.9	676.1	631.0
Equity in earnings of unconsolidated entities									0.0	0.0
Gain on sale of assets									0.0	0.0
Other (income) expense									(1.5)	(0.2)	1.4
Income before income taxes									1,165.5	1,367.3	1,110.3
Income tax expense (benefit)									279.5	406.1	388.6
Equity in net income of subsidiaries, net of tax									0.0	0.0	0.0
Net income									886.0	961.2	721.7
Net income attributable to noncontrolling interests									0.0	0.0
Net income attributable to D.R. Horton, Inc.									886.0	961.2
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									906.1	488.0	387.0
Unaudited Supplemental Consolidating Statement of Operations
Cost of sales									373.3	74.9	24.1
Selling, general and administrative expense									356.3	335.1	256.3
Equity in earnings of unconsolidated entities									(0.5)	(5.3)
Gain on sale of assets									(49.2)	(16.4)
Other (income) expense									(24.9)	(39.1)	(15.8)
Income before income taxes									251.1	138.8	122.4
Income tax expense (benefit)									57.3	27.1	45.9
Equity in net income of subsidiaries, net of tax									0.0	0.0	0.0
Net income									193.8	111.7	76.5
Net income attributable to noncontrolling interests									(4.1)	3.1
Net income attributable to D.R. Horton, Inc.									197.9	108.6
Consolidation, Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									(336.2)	(50.7)	(9.1)
Unaudited Supplemental Consolidating Statement of Operations
Cost of sales									(304.2)	(41.8)	(8.5)
Selling, general and administrative expense									0.0	0.0	0.0
Equity in earnings of unconsolidated entities									0.0	2.5
Gain on sale of assets									(2.7)	0.0
Other (income) expense									0.0	0.0	0.0
Income before income taxes									(29.3)	(11.4)	(0.6)
Income tax expense (benefit)									(7.0)	(3.4)	(0.2)
Equity in net income of subsidiaries, net of tax									(1,084.0)	(1,069.7)	(798.2)
Net income									(1,106.3)	(1,077.7)	$ (798.6)
Net income attributable to noncontrolling interests									4.2	(1.1)
Net income attributable to D.R. Horton, Inc.									$ (1,110.5)	$ (1,076.6)