Supplemental Guarantor Information - Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Financial Services [Abstract]
Income before income taxes	$ 444.5	$ 378.6	$ 1,116.5	$ 920.4
Income tax expense	155.5	128.8	391.4	317.8
Net income	289.0	249.8	725.1	602.6
Comprehensive income	289.0	249.8	725.1	601.2
Eliminations [Member]
Financial Services [Abstract]
Income before income taxes	(317.0)	(306.0)	(851.8)	(751.1)
Income tax expense	(111.1)	(105.0)	(299.2)	(259.7)
Net income	(205.9)	(201.0)	(552.6)	(491.4)
Comprehensive income	(205.9)	(201.0)	(552.6)	(491.4)
D.R. Horton, Inc. [Member]
Financial Services [Abstract]
Income before income taxes	444.5	381.3	1,116.5	925.6
Income tax expense	155.5	130.6	391.4	319.6
Net income	289.0	250.7	725.1	606.0
Comprehensive income	289.0	250.7	725.1	604.6
Guarantor Subsidiaries [Member]
Financial Services [Abstract]
Income before income taxes	291.7	274.5	768.4	681.8
Income tax expense	101.3	92.4	267.7	234.0
Net income	190.4	182.1	500.7	447.8
Comprehensive income	190.4	182.1	500.7	447.8
Non-Guarantor Subsidiaries [Member]
Financial Services [Abstract]
Income before income taxes	25.3	28.8	83.4	64.1
Income tax expense	9.8	10.8	31.5	23.9
Net income	15.5	18.0	51.9	40.2
Comprehensive income	15.5	18.0	51.9	40.2
Homebuilding [Member]
Homebuilding:
Revenues	3,684.5	3,148.8	9,675.0	8,210.8
Cost of sales	2,961.1	2,523.0	7,778.9	6,584.3
Total gross profit	723.4	625.8	1,896.1	1,626.5
Selling, general and administrative expense	309.5	279.3	872.4	778.4
Equity in (income) of subsidiaries	0.0	0.0	0.0	0.0
Other (income) expense	(1.3)	(1.9)	(7.8)	(11.2)
Financial Services [Abstract]
Income before income taxes	415.2	348.4	1,031.5	859.3
Homebuilding [Member] | Eliminations [Member]
Homebuilding:
Revenues	0.0	(10.6)	0.0	(16.0)
Cost of sales	0.0	(7.9)	0.0	(10.8)
Total gross profit	0.0	(2.7)	0.0	(5.2)
Selling, general and administrative expense	0.0	0.0	0.0	0.0
Equity in (income) of subsidiaries	317.0	303.3	851.8	745.9
Other (income) expense	0.0	0.0	0.0	0.0
Financial Services [Abstract]
Income before income taxes	(317.0)	(306.0)	(851.8)	(751.1)
Homebuilding [Member] | D.R. Horton, Inc. [Member]
Homebuilding:
Revenues	1,332.0	1,040.8	3,344.5	2,700.7
Cost of sales	1,056.7	836.9	2,670.0	2,170.5
Total gross profit	275.3	203.9	674.5	530.2
Selling, general and administrative expense	148.5	126.6	415.7	357.4
Equity in (income) of subsidiaries	(317.0)	(303.3)	(851.8)	(745.9)
Other (income) expense	(0.7)	(0.7)	(5.9)	(6.9)
Financial Services [Abstract]
Income before income taxes	444.5	381.3	1,116.5	925.6
Homebuilding [Member] | Guarantor Subsidiaries [Member]
Homebuilding:
Revenues	2,352.3	2,118.6	6,293.0	5,526.1
Cost of sales	1,900.9	1,693.2	5,072.9	4,429.3
Total gross profit	451.4	425.4	1,220.1	1,096.8
Selling, general and administrative expense	159.9	151.5	452.8	418.4
Equity in (income) of subsidiaries	0.0	0.0	0.0	0.0
Other (income) expense	(0.2)	(0.6)	(1.1)	(3.4)
Financial Services [Abstract]
Income before income taxes	291.7	274.5	768.4	681.8
Homebuilding [Member] | Non-Guarantor Subsidiaries [Member]
Homebuilding:
Revenues	0.2	0.0	37.5	0.0
Cost of sales	3.5	0.8	36.0	(4.7)
Total gross profit	(3.3)	(0.8)	1.5	4.7
Selling, general and administrative expense	1.1	1.2	3.9	2.6
Equity in (income) of subsidiaries	0.0	0.0	0.0	0.0
Other (income) expense	(0.4)	(0.6)	(0.8)	(0.9)
Financial Services [Abstract]
Income before income taxes	(4.0)	(1.4)	(1.6)	3.0
Financial Services and Other [Member]
Financial Services [Abstract]
Revenues	91.9	83.1	256.9	205.4
General and administrative expense	65.0	57.5	183.1	157.1
Interest and other (income) expense	(2.4)	(4.6)	(11.2)	(12.8)
Income before income taxes	29.3	30.2	85.0	61.1
Financial Services and Other [Member] | Eliminations [Member]
Financial Services [Abstract]
Revenues	0.0	0.0	0.0	0.0
General and administrative expense	0.0	0.0	0.0	0.0
Interest and other (income) expense	0.0	0.0	0.0	0.0
Income before income taxes	0.0	0.0	0.0	0.0
Financial Services and Other [Member] | D.R. Horton, Inc. [Member]
Financial Services [Abstract]
Revenues	0.0	0.0	0.0	0.0
General and administrative expense	0.0	0.0	0.0	0.0
Interest and other (income) expense	0.0	0.0	0.0	0.0
Income before income taxes	0.0	0.0	0.0	0.0
Financial Services and Other [Member] | Guarantor Subsidiaries [Member]
Financial Services [Abstract]
Revenues	0.0	0.0	0.0	0.0
General and administrative expense	0.0	0.0	0.0	0.0
Interest and other (income) expense	0.0	0.0	0.0	0.0
Income before income taxes	0.0	0.0	0.0	0.0
Financial Services and Other [Member] | Non-Guarantor Subsidiaries [Member]
Financial Services [Abstract]
Revenues	91.9	83.1	256.9	205.4
General and administrative expense	65.0	57.5	183.1	157.1
Interest and other (income) expense	(2.4)	(4.6)	(11.2)	(12.8)
Income before income taxes	$ 29.3	$ 30.2	$ 85.0	$ 61.1