Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended					9 Months Ended
	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenues	$ 4,435.3		$ 3,776.4			$ 11,562.9	$ 9,931.9
Cost of sales	3,397.2		2,961.1			8,939.0	7,778.9
Selling, general and administrative expense	434.9		374.5			1,219.9	1,055.5
Equity in earnings of unconsolidated entities	(0.4)		0.0			(3.1)	0.0
Gain on sale of assets	0.0		0.0			(14.5)	0.0
Other (income) expense	(12.6)		(3.7)			(30.7)	(19.0)
Income before income taxes	616.2		444.5			1,452.3	1,116.5
Income tax expense	162.5		155.5			458.9	391.4
Net income	453.7		289.0			993.4	725.1
Net loss attributable to noncontrolling interests	(0.1)		0.0			(0.7)	0.0
Net income attributable to D.R. Horton, Inc.	$ 453.8		$ 289.0			$ 994.1	$ 725.1
Basic net income per common share attributable to D.R. Horton, Inc. (in dollars per share)	$ 1.20		$ 0.77			$ 2.64	$ 1.94
Weighted average number of common shares	377.4		374.8			376.6	374.1
Diluted net income per common share attributable to D.R. Horton, Inc. (in dollars per share)	$ 1.18		$ 0.76			$ 2.59	$ 1.92
Adjusted weighted average number of common shares	383.4		379.4			383.6	378.5
Cash dividends declared per common share (in dollars per share)	$ 0.125	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.375	$ 0.30