Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Millions, $ 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
Income Statement [Abstract]
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
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	156.2	153.1	108.4	89.0	138.8	162.5	94.0	202.4	506.7	597.7	563.7
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
Other comprehensive income, net of income tax:
Basic net income per common share attributable to D.R. Horton, Inc.	$ 1.37	$ 1.28	$ 0.94	$ 0.77	$ 1.24	$ 1.20	$ 0.93	$ 0.50	$ 4.34	$ 3.88	$ 2.77
Weighted average number of common shares									372.6	376.6	374.3
Diluted net income per common share attributable to D.R. Horton, Inc.	$ 1.35	$ 1.26	$ 0.93	$ 0.76	$ 1.22	$ 1.18	$ 0.91	$ 0.49	$ 4.29	$ 3.81	$ 2.74
Adjusted weighted average number of common shares									377.4	383.4	378.9