Supplemental Guarantor Information - Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Consolidating Statement of Operations
Revenues	$ 3,332.7	$ 2,904.2
Cost of sales	2,580.1	2,267.9
Selling, general and administrative expense	384.2	325.9
Equity in earnings of unconsolidated entities	(2.3)	0.0
Other (income) expense	(20.5)	(7.7)
Income before income taxes	391.2	318.1
Income tax expense	202.4	111.2
Income (Loss) from subsidiaries, Net of Tax	0.0	0.0
Net income	188.8	206.9
Net loss attributable to noncontrolling interests	(0.5)	0.0
Net Income (Loss) Attributable to Parent	189.3	206.9
Eliminations [Member]
Consolidating Statement of Operations
Revenues	0.0	0.0
Cost of sales	0.0	0.0
Selling, general and administrative expense	0.0	0.0
Equity in earnings of unconsolidated entities	0.0
Other (income) expense	0.0	0.0
Income before income taxes	0.0	0.0
Income tax expense	0.0	0.0
Income (Loss) from subsidiaries, Net of Tax	(143.3)	(165.9)
Net income	(143.3)	(165.9)
Net loss attributable to noncontrolling interests	0.0
Net Income (Loss) Attributable to Parent	(143.3)
D.R. Horton, Inc. [Member]
Consolidating Statement of Operations
Revenues	1,163.8	918.1
Cost of sales	915.4	735.4
Selling, general and administrative expense	152.2	124.0
Equity in earnings of unconsolidated entities	0.0
Other (income) expense	(0.4)	(4.1)
Income before income taxes	96.6	62.8
Income tax expense	51.1	21.8
Income (Loss) from subsidiaries, Net of Tax	143.3	165.9
Net income	188.8	206.9
Net loss attributable to noncontrolling interests	0.0
Net Income (Loss) Attributable to Parent	188.8
D.R. Horton, Inc. [Member] | Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Prior Period Reclassification Adjustment		89.4
Guarantor Subsidiaries [Member]
Consolidating Statement of Operations
Revenues	2,052.4	1,896.1
Cost of sales	1,640.0	1,524.7
Selling, general and administrative expense	151.5	143.3
Equity in earnings of unconsolidated entities	0.0
Other (income) expense	0.0	0.0
Income before income taxes	260.9	228.1
Income tax expense	137.9	79.2
Income (Loss) from subsidiaries, Net of Tax	0.0	0.0
Net income	123.0	148.9
Net loss attributable to noncontrolling interests	0.0
Net Income (Loss) Attributable to Parent	123.0
Non-Guarantor Subsidiaries [Member]
Consolidating Statement of Operations
Revenues	116.5	90.0
Cost of sales	24.7	7.8
Selling, general and administrative expense	80.5	58.6
Equity in earnings of unconsolidated entities	(2.3)
Other (income) expense	(20.1)	(3.6)
Income before income taxes	33.7	27.2
Income tax expense	13.4	10.2
Income (Loss) from subsidiaries, Net of Tax	0.0	0.0
Net income	20.3	$ 17.0
Net loss attributable to noncontrolling interests	(0.5)
Net Income (Loss) Attributable to Parent	$ 20.8