Supplemental Guarantor Information - Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015
ASSETS
Cash and cash equivalents	$ 993.2	$ 1,303.2	$ 1,224.1	$ 1,383.8
Investments in subsidiaries	0.0	0.0
Property and equipment, net	248.1	195.4
Other assets	521.2	499.6
Intercompany receivables	0.0	0.0
Total assets	11,921.1	11,558.9
LIABILITIES & EQUITY
Accounts payable and other liabilities	1,478.6	1,494.6
Intercompany payables	0.0	0.0
Notes payable	3,222.4	3,271.3
Total liabilities	4,701.0	4,765.9
Stockholders’ equity	7,219.6	6,792.5
Noncontrolling interests	0.5	0.5
Total equity	7,220.1	6,793.0
Total liabilities and equity	11,921.1	11,558.9
Eliminations [Member]
ASSETS
Cash and cash equivalents	0.0	0.0	0.0	0.0
Investments in subsidiaries	(4,414.7)	(4,118.6)
Property and equipment, net	(5.2)	(5.2)
Other assets	0.0	0.0
Intercompany receivables	(1,485.4)	(1,604.5)
Total assets	(5,905.3)	(5,728.3)
LIABILITIES & EQUITY
Accounts payable and other liabilities	(1.8)	(1.8)
Intercompany payables	(1,485.4)	(1,604.5)
Notes payable	0.0	0.0
Total liabilities	(1,487.2)	(1,606.3)
Stockholders’ equity	(4,418.1)	(4,122.0)
Noncontrolling interests	0.0	0.0
Total equity	(4,418.1)	(4,122.0)
Total liabilities and equity	(5,905.3)	(5,728.3)
D.R. Horton, Inc. [Member]
ASSETS
Cash and cash equivalents	812.5	1,076.4	1,036.3	1,217.7
Investments in subsidiaries	4,414.7	4,118.6
Property and equipment, net	94.0	72.0
Other assets	181.1	168.7
Intercompany receivables	1,485.4	1,604.5
Total assets	10,442.1	10,029.0
LIABILITIES & EQUITY
Accounts payable and other liabilities	427.7	444.1
Intercompany payables	0.0	0.0
Notes payable	2,791.4	2,789.0
Total liabilities	3,219.1	3,233.1
Stockholders’ equity	7,223.0	6,795.9
Noncontrolling interests	0.0	0.0
Total equity	7,223.0	6,795.9
Total liabilities and equity	10,442.1	10,029.0
Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	95.2	154.0	114.0	94.6
Investments in subsidiaries	0.0	0.0
Property and equipment, net	56.5	49.9
Other assets	268.9	274.2
Intercompany receivables	0.0	0.0
Total assets	6,426.1	6,300.0
LIABILITIES & EQUITY
Accounts payable and other liabilities	918.6	933.1
Intercompany payables	1,245.2	1,417.1
Notes payable	12.0	9.3
Total liabilities	2,175.8	2,359.5
Stockholders’ equity	4,250.3	3,940.5
Noncontrolling interests	0.0	0.0
Total equity	4,250.3	3,940.5
Total liabilities and equity	6,426.1	6,300.0
Non-Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	85.5	72.8	$ 73.8	$ 71.5
Investments in subsidiaries	0.0	0.0
Property and equipment, net	102.8	78.7
Other assets	71.2	56.7
Intercompany receivables	0.0	0.0
Total assets	958.2	958.2
LIABILITIES & EQUITY
Accounts payable and other liabilities	134.1	119.2
Intercompany payables	240.2	187.4
Notes payable	419.0	473.0
Total liabilities	793.3	779.6
Stockholders’ equity	164.4	178.1
Noncontrolling interests	0.5	0.5
Total equity	164.9	178.6
Total liabilities and equity	958.2	958.2
Homebuilding [Member]
ASSETS
Cash and cash equivalents	947.9	1,271.8
Restricted cash	11.1	9.5
Inventories	9,038.1	8,340.9
Deferred income taxes	451.6	476.3
Property and equipment, net	167.6	139.5
Other assets	463.4	456.2
Goodwill	80.0	80.0
Total assets	11,159.7	10,774.2
LIABILITIES & EQUITY
Notes payable	2,803.4	2,798.3
Total liabilities	4,231.4	4,252.4
Homebuilding [Member] | Eliminations [Member]
ASSETS
Restricted cash	0.0	0.0
Inventories	0.0	0.0
Deferred income taxes	0.0	0.0
Goodwill	0.0	0.0
Homebuilding [Member] | D.R. Horton, Inc. [Member]
ASSETS
Restricted cash	8.7	7.4
Inventories	3,287.5	2,822.1
Deferred income taxes	158.2	159.3
Goodwill	0.0	0.0
Homebuilding [Member] | Guarantor Subsidiaries [Member]
ASSETS
Restricted cash	2.4	2.1
Inventories	5,632.6	5,425.7
Deferred income taxes	290.5	314.1
Goodwill	80.0	80.0
Homebuilding [Member] | Non-Guarantor Subsidiaries [Member]
ASSETS
Restricted cash	0.0	0.0
Inventories	118.0	93.1
Deferred income taxes	2.9	2.9
Goodwill	0.0	0.0
Financial Services and Other [Member]
ASSETS
Cash and cash equivalents	45.3	31.4
Property and equipment, net	80.5	55.9
Other assets	57.8	43.4
Mortgage loans held for sale	577.8	654.0
Total assets	761.4	784.7
LIABILITIES & EQUITY
Total liabilities	469.6	513.5
Financial Services and Other [Member] | Eliminations [Member]
ASSETS
Mortgage loans held for sale	0.0	0.0
Financial Services and Other [Member] | D.R. Horton, Inc. [Member]
ASSETS
Mortgage loans held for sale	0.0	0.0
Financial Services and Other [Member] | Guarantor Subsidiaries [Member]
ASSETS
Mortgage loans held for sale	0.0	0.0
Financial Services and Other [Member] | Non-Guarantor Subsidiaries [Member]
ASSETS
Mortgage loans held for sale	$ 577.8	$ 654.0