Supplemental Guarantor Information - Statement of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$ (140.8)	$ 26.9
INVESTING ACTIVITIES
Purchases of property and equipment	(57.5)	(40.4)
Increase in restricted cash	(8.9)	(1.7)
Net principal decrease (increase) of other mortgage loans and real estate owned	1.0	(0.4)
(Purchases of) proceeds from debt securities collateralized by residential real estate	(3.9)	35.8
Intercompany advances	0.0	0.0
Payments related to acquisition of a business	(4.1)	0.0
Net cash provided by (used in) investing activities	(73.4)	(6.7)
FINANCING ACTIVITIES
Proceeds from notes payable	0.0	17.6
Repayment of notes payable	(54.5)	(170.6)
Intercompany advances	0.0	0.0
Proceeds from stock associated with certain employee benefit plans	24.7	28.4
Excess income tax benefit from employee stock awards	8.7	3.9
Cash dividends paid	(74.7)	(59.2)
Net cash (used in) provided by financing activities	(95.8)	(179.9)
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(310.0)	(159.7)
Cash and cash equivalents at beginning of period	1,303.2	1,383.8
Cash and cash equivalents at end of period	993.2	1,224.1
Eliminations [Member]
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	(50.0)	(45.4)
INVESTING ACTIVITIES
Purchases of property and equipment	0.0	5.4
Increase in restricted cash	0.0	0.0
Net principal decrease (increase) of other mortgage loans and real estate owned	0.0	0.0
(Purchases of) proceeds from debt securities collateralized by residential real estate	0.0	0.0
Intercompany advances	(123.8)	(43.9)
Payments related to acquisition of a business	0.0
Net cash provided by (used in) investing activities	(123.8)	(38.5)
FINANCING ACTIVITIES
Proceeds from notes payable		0.0
Repayment of notes payable	0.0	0.0
Intercompany advances	123.8	43.9
Proceeds from stock associated with certain employee benefit plans	0.0	0.0
Excess income tax benefit from employee stock awards	0.0	0.0
Cash dividends paid	50.0	40.0
Net cash (used in) provided by financing activities	173.8	83.9
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	0.0	0.0
Cash and cash equivalents at beginning of period	0.0	0.0
Cash and cash equivalents at end of period	0.0	0.0
D.R. Horton, Inc. [Member]
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	(308.7)	(42.4)
INVESTING ACTIVITIES
Purchases of property and equipment	(28.4)	(20.5)
Increase in restricted cash	(1.3)	(1.2)
Net principal decrease (increase) of other mortgage loans and real estate owned	0.0	0.0
(Purchases of) proceeds from debt securities collateralized by residential real estate	(3.9)	35.8
Intercompany advances	123.8	43.9
Payments related to acquisition of a business	(4.1)
Net cash provided by (used in) investing activities	86.1	58.0
FINANCING ACTIVITIES
Proceeds from notes payable		0.0
Repayment of notes payable	0.0	(170.1)
Intercompany advances	0.0	0.0
Proceeds from stock associated with certain employee benefit plans	24.7	28.4
Excess income tax benefit from employee stock awards	8.7	3.9
Cash dividends paid	(74.7)	(59.2)
Net cash (used in) provided by financing activities	(41.3)	(197.0)
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(263.9)	(181.4)
Cash and cash equivalents at beginning of period	1,076.4	1,217.7
Cash and cash equivalents at end of period	812.5	1,036.3
Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	130.3	84.0
INVESTING ACTIVITIES
Purchases of property and equipment	(11.7)	(6.1)
Increase in restricted cash	(0.3)	(0.5)
Net principal decrease (increase) of other mortgage loans and real estate owned	0.0	0.0
(Purchases of) proceeds from debt securities collateralized by residential real estate	0.0	0.0
Intercompany advances	0.0	0.0
Payments related to acquisition of a business	0.0
Net cash provided by (used in) investing activities	(12.0)	(6.6)
FINANCING ACTIVITIES
Proceeds from notes payable		0.0
Repayment of notes payable	(0.5)	(0.5)
Intercompany advances	(176.6)	(57.5)
Proceeds from stock associated with certain employee benefit plans	0.0	0.0
Excess income tax benefit from employee stock awards	0.0	0.0
Cash dividends paid	0.0	0.0
Net cash (used in) provided by financing activities	(177.1)	(58.0)
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(58.8)	19.4
Cash and cash equivalents at beginning of period	154.0	94.6
Cash and cash equivalents at end of period	95.2	114.0
Non-Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	87.6	30.7
INVESTING ACTIVITIES
Purchases of property and equipment	(17.4)	(19.2)
Increase in restricted cash	(7.3)	0.0
Net principal decrease (increase) of other mortgage loans and real estate owned	1.0	(0.4)
(Purchases of) proceeds from debt securities collateralized by residential real estate	0.0	0.0
Intercompany advances	0.0	0.0
Payments related to acquisition of a business	0.0
Net cash provided by (used in) investing activities	(23.7)	(19.6)
FINANCING ACTIVITIES
Proceeds from notes payable		17.6
Repayment of notes payable	(54.0)	0.0
Intercompany advances	52.8	13.6
Proceeds from stock associated with certain employee benefit plans	0.0	0.0
Excess income tax benefit from employee stock awards	0.0	0.0
Cash dividends paid	(50.0)	(40.0)
Net cash (used in) provided by financing activities	(51.2)	(8.8)
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	12.7	2.3
Cash and cash equivalents at beginning of period	72.8	71.5
Cash and cash equivalents at end of period	$ 85.5	$ 73.8