Supplemental Guarantor Information - Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
ASSETS
Cash and cash equivalents	$ 1,494.3	$ 1,473.1
Restricted cash	19.7	32.9
Investments in subsidiaries	0.0	0.0
Total inventories	11,282.0	10,395.0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	6.5	11.0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	1,072.0	796.4
Deferred income taxes, net	163.1	194.0
Property and equipment, net	462.2	401.1
Other assets	943.3	701.9
Goodwill	163.5	109.2
Intercompany receivables	0.0	0.0
Total assets	15,606.6	14,114.6
LIABILITIES & EQUITY
Accounts payable and other liabilities	1,912.1	1,752.2
Intercompany payables	0.0	0.0
Notes payable	3,399.4	3,203.5
Total liabilities	5,311.5	4,955.7
Total stockholders' equity	10,020.9	8,984.4
Noncontrolling interests	274.2	174.5
Total equity	10,295.1	9,158.9	$ 7,747.6	$ 6,793.0
Total liabilities and equity	15,606.6	14,114.6
Consolidation, Eliminations [Member]
ASSETS
Cash and cash equivalents	0.0	0.0
Restricted cash	0.0	0.0
Investments in subsidiaries	(7,349.8)	(6,344.9)
Total inventories	(35.3)	(11.2)
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0.0	0.0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0.0	0.0
Deferred income taxes, net	5.1	2.5
Property and equipment, net	(6.0)	(6.9)
Other assets	(89.5)	(45.2)
Goodwill	0.0	0.0
Intercompany receivables	(825.9)	(273.5)
Total assets	(8,301.4)	(6,679.2)
LIABILITIES & EQUITY
Accounts payable and other liabilities	(91.7)	(49.1)
Intercompany payables	(825.9)	(273.5)
Notes payable	0.0	0.0
Total liabilities	(917.6)	(322.6)
Total stockholders' equity	(7,387.1)	(6,355.6)
Noncontrolling interests	3.3	(1.0)
Total equity	(7,383.8)	(6,356.6)
Total liabilities and equity	(8,301.4)	(6,679.2)
D.R Horton, Inc. [Member]
ASSETS
Cash and cash equivalents	877.1	908.1
Restricted cash	6.8	6.6
Investments in subsidiaries	7,349.8	6,344.9
Total inventories	4,166.1	4,037.1
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0.0	0.0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0.0	0.0
Deferred income taxes, net	60.6	69.2
Property and equipment, net	123.8	111.2
Other assets	398.7	306.6
Goodwill	0.0	0.0
Intercompany receivables	0.0	246.2
Total assets	12,982.9	12,029.9
LIABILITIES & EQUITY
Accounts payable and other liabilities	616.1	590.8
Intercompany payables	352.7	0.0
Notes payable	1,955.9	2,443.9
Total liabilities	2,924.7	3,034.7
Total stockholders' equity	10,058.2	8,995.2
Noncontrolling interests	0.0	0.0
Total equity	10,058.2	8,995.2
Total liabilities and equity	12,982.9	12,029.9
Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	115.8	158.7
Restricted cash	1.3	2.0
Investments in subsidiaries	0.0	0.0
Total inventories	5,890.7	5,824.1
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0.0	0.0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0.0	0.0
Deferred income taxes, net	89.4	105.0
Property and equipment, net	76.6	66.1
Other assets	459.7	361.3
Goodwill	134.3	80.0
Intercompany receivables	825.9	27.3
Total assets	7,593.7	6,624.5
LIABILITIES & EQUITY
Accounts payable and other liabilities	1,071.3	1,000.4
Intercompany payables	0.0	0.0
Notes payable	14.2	2.1
Total liabilities	1,085.5	1,002.5
Total stockholders' equity	6,508.2	5,622.0
Noncontrolling interests	0.0	0.0
Total equity	6,508.2	5,622.0
Total liabilities and equity	7,593.7	6,624.5
Non-Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	501.4	406.3
Restricted cash	11.6	24.3
Investments in subsidiaries	0.0	0.0
Total inventories	1,260.5	545.0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	6.5	11.0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	1,072.0	796.4
Deferred income taxes, net	8.0	17.3
Property and equipment, net	267.8	230.7
Other assets	174.4	79.2
Goodwill	29.2	29.2
Intercompany receivables	0.0	0.0
Total assets	3,331.4	2,139.4
LIABILITIES & EQUITY
Accounts payable and other liabilities	316.4	210.1
Intercompany payables	473.2	273.5
Notes payable	1,429.3	757.5
Total liabilities	2,218.9	1,241.1
Total stockholders' equity	841.6	722.8
Noncontrolling interests	270.9	175.5
Total equity	1,112.5	898.3
Total liabilities and equity	$ 3,331.4	$ 2,139.4