Supplemental Guarantor Information - Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
ASSETS
Cash and cash equivalents	$ 737.0	$ 1,473.1
Restricted cash	31.3	32.9
Investment in subsidiaries	0.0	0.0
Inventories	11,595.6	10,395.0
Mortgage loans held for sale	622.2	796.4
Deferred income taxes, net	181.4	194.0
Property and equipment, net	391.1	401.1
Other assets	818.8	712.9
Goodwill	158.4	109.2
Intercompany receivables	0.0	0.0
Total assets	14,535.8	14,114.6
LIABILITIES & EQUITY
Accounts payable and other liabilities	1,895.3	1,752.2
Intercompany payables	0.0	0.0
Notes payable	3,342.3	3,203.5
Total liabilities	5,237.6	4,955.7
Stockholders’ equity	9,124.7	8,984.4
Noncontrolling interests	173.5	174.5
Total equity	9,298.2	9,158.9	$ 8,055.4	$ 7,747.6
Total liabilities and equity	14,535.8	14,114.6
Eliminations [Member]
ASSETS
Cash and cash equivalents	0.0	0.0
Restricted cash	0.0	0.0
Investment in subsidiaries	(6,540.2)	(6,344.9)
Inventories	(18.0)	(11.2)
Mortgage loans held for sale	0.0	0.0
Deferred income taxes, net	1.8	2.5
Property and equipment, net	(6.9)	(6.9)
Other assets	(62.9)	(45.2)
Goodwill	0.0	0.0
Intercompany receivables	(676.1)	(273.5)
Total assets	(7,302.3)	(6,679.2)
LIABILITIES & EQUITY
Accounts payable and other liabilities	(71.5)	(49.1)
Intercompany payables	(676.1)	(273.5)
Notes payable	0.0	0.0
Total liabilities	(747.6)	(322.6)
Stockholders’ equity	(6,553.8)	(6,355.6)
Noncontrolling interests	(0.9)	(1.0)
Total equity	(6,554.7)	(6,356.6)
Total liabilities and equity	(7,302.3)	(6,679.2)
D.R. Horton, Inc. [Member]
ASSETS
Cash and cash equivalents	458.8	908.1
Restricted cash	6.8	6.6
Investment in subsidiaries	6,540.2	6,344.9
Inventories	4,368.0	4,037.1
Mortgage loans held for sale	0.0	0.0
Deferred income taxes, net	64.2	69.2
Property and equipment, net	112.6	111.2
Other assets	322.7	306.6
Goodwill	0.0	0.0
Intercompany receivables	676.1	246.2
Total assets	12,549.4	12,029.9
LIABILITIES & EQUITY
Accounts payable and other liabilities	663.5	590.8
Intercompany payables	0.0	0.0
Notes payable	2,747.6	2,443.9
Total liabilities	3,411.1	3,034.7
Stockholders’ equity	9,138.3	8,995.2
Noncontrolling interests	0.0	0.0
Total equity	9,138.3	8,995.2
Total liabilities and equity	12,549.4	12,029.9
Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	32.8	158.7
Restricted cash	1.9	2.0
Investment in subsidiaries	0.0	0.0
Inventories	6,516.3	5,824.1
Mortgage loans held for sale	0.0	0.0
Deferred income taxes, net	98.3	105.0
Property and equipment, net	82.2	66.1
Other assets	390.7	361.3
Goodwill	129.2	80.0
Intercompany receivables	0.0	27.3
Total assets	7,251.4	6,624.5
LIABILITIES & EQUITY
Accounts payable and other liabilities	1,057.8	1,000.4
Intercompany payables	391.2	0.0
Notes payable	1.1	2.1
Total liabilities	1,450.1	1,002.5
Stockholders’ equity	5,801.3	5,622.0
Noncontrolling interests	0.0	0.0
Total equity	5,801.3	5,622.0
Total liabilities and equity	7,251.4	6,624.5
Non-Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	245.4	406.3
Restricted cash	22.6	24.3
Investment in subsidiaries	0.0	0.0
Inventories	729.3	545.0
Mortgage loans held for sale	622.2	796.4
Deferred income taxes, net	17.1	17.3
Property and equipment, net	203.2	230.7
Other assets	168.3	90.2
Goodwill	29.2	29.2
Intercompany receivables	0.0	0.0
Total assets	2,037.3	2,139.4
LIABILITIES & EQUITY
Accounts payable and other liabilities	245.5	210.1
Intercompany payables	284.9	273.5
Notes payable	593.6	757.5
Total liabilities	1,124.0	1,241.1
Stockholders’ equity	738.9	722.8
Noncontrolling interests	174.4	175.5
Total equity	913.3	898.3
Total liabilities and equity	$ 2,037.3	$ 2,139.4