Supplemental Guarantor Information - Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$ 618.0	$ 700.4	$ (661.4)
INVESTING ACTIVITIES
Purchases of property and equipment	(86.1)	(56.1)	(100.2)
Proceeds from the sale of property and equipment to a related party	0.0	56.0	0.0
Decrease (increase) in restricted cash	0.2	(0.7)	67.8
Net principal decrease (increase) of other mortgage loans and real estate owned	19.7	(8.9)	(5.6)
Proceeds from sale (purchases) of debt securities collateralized by residential real estate	35.8	(14.8)	0.0
Intercompany advances	0.0	0.0	0.0
Payments related to acquisition of a business	(82.2)	(70.9)	(244.1)
Net cash used in investing activities	(112.6)	(95.4)	(282.1)
FINANCING ACTIVITIES
Proceeds from Notes Payable	0.0	1,590.7	1,427.6
Repayments of Notes Payable	(549.7)	(1,456.2)	(796.9)
Intercompany advances	0.0	0.0	0.0
Proceeds from stock associated with certain employee benefit plans	72.4	61.8	45.2
Income tax benefit from stock option exercises	10.0	12.3	0.6
Cash dividends paid	(118.7)	(91.6)	(48.6)
Net cash provided by (used in) financing activities	(586.0)	117.0	627.9
Increase (decrease) in cash and cash equivalents	(80.6)	722.0	(315.6)
Cash and cash equivalents at beginning of year	1,383.8	661.8	977.4
Cash and cash equivalents at end of year	1,303.2	1,383.8	661.8
Consolidation, Eliminations [Member]
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	(77.8)	(31.6)	(52.6)
INVESTING ACTIVITIES
Purchases of property and equipment	16.0	0.0	0.0
Proceeds from the sale of property and equipment to a related party		0.0
Decrease (increase) in restricted cash	0.0	0.0	0.0
Net principal decrease (increase) of other mortgage loans and real estate owned	0.0	0.0	0.0
Proceeds from sale (purchases) of debt securities collateralized by residential real estate	0.0	0.0
Intercompany advances	(409.9)	(444.7)	385.7
Payments related to acquisition of a business	0.0	0.0	0.0
Net cash used in investing activities	(393.9)	(444.7)	385.7
FINANCING ACTIVITIES
Proceeds from Notes Payable		0.0	0.0
Repayments of Notes Payable	0.0	0.0	0.0
Intercompany advances	409.9	444.7	(385.7)
Proceeds from stock associated with certain employee benefit plans	0.0	0.0	0.0
Income tax benefit from stock option exercises	0.0	0.0	0.0
Cash dividends paid	61.8	31.6	52.6
Net cash provided by (used in) financing activities	471.7	476.3	(333.1)
Increase (decrease) in cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents at beginning of year	0.0	0.0	0.0
Cash and cash equivalents at end of year	0.0	0.0	0.0
D.R Horton, Inc. [Member]
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	115.1	308.2	(257.4)
INVESTING ACTIVITIES
Purchases of property and equipment	(40.7)	(24.5)	(63.9)
Proceeds from the sale of property and equipment to a related party		56.0
Decrease (increase) in restricted cash	0.0	(0.4)	69.7
Net principal decrease (increase) of other mortgage loans and real estate owned	0.0	0.0	0.0
Proceeds from sale (purchases) of debt securities collateralized by residential real estate	35.8	(14.8)
Intercompany advances	409.9	444.7	(385.7)
Payments related to acquisition of a business	(82.2)	(70.9)	(244.1)
Net cash used in investing activities	322.8	390.1	(624.0)
FINANCING ACTIVITIES
Proceeds from Notes Payable		1,472.0	1,307.0
Repayments of Notes Payable	(542.9)	(1,432.5)	(796.8)
Intercompany advances	0.0	0.0	0.0
Proceeds from stock associated with certain employee benefit plans	72.4	61.8	45.2
Income tax benefit from stock option exercises	10.0	12.3	0.6
Cash dividends paid	(118.7)	(91.6)	(48.6)
Net cash provided by (used in) financing activities	(579.2)	22.0	507.4
Increase (decrease) in cash and cash equivalents	(141.3)	720.3	(374.0)
Cash and cash equivalents at beginning of year	1,217.7	497.4	871.4
Cash and cash equivalents at end of year	1,076.4	1,217.7	497.4
Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	596.7	530.1	(293.9)
INVESTING ACTIVITIES
Purchases of property and equipment	(14.3)	(24.8)	(28.0)
Proceeds from the sale of property and equipment to a related party		0.0
Decrease (increase) in restricted cash	0.2	(0.3)	(0.9)
Net principal decrease (increase) of other mortgage loans and real estate owned	0.0	0.0	0.0
Proceeds from sale (purchases) of debt securities collateralized by residential real estate	0.0	0.0
Intercompany advances	0.0	0.0	0.0
Payments related to acquisition of a business	0.0	0.0	0.0
Net cash used in investing activities	(14.1)	(25.1)	(28.9)
FINANCING ACTIVITIES
Proceeds from Notes Payable		0.0	0.0
Repayments of Notes Payable	(1.9)	(6.3)	0.0
Intercompany advances	(521.3)	(493.6)	373.9
Proceeds from stock associated with certain employee benefit plans	0.0	0.0	0.0
Income tax benefit from stock option exercises	0.0	0.0	0.0
Cash dividends paid	0.0	0.0	0.0
Net cash provided by (used in) financing activities	(523.2)	(499.9)	373.9
Increase (decrease) in cash and cash equivalents	59.4	5.1	51.1
Cash and cash equivalents at beginning of year	94.6	89.5	38.4
Cash and cash equivalents at end of year	154.0	94.6	89.5
Non-Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	(16.0)	(106.3)	(57.5)
INVESTING ACTIVITIES
Purchases of property and equipment	(47.1)	(6.8)	(8.3)
Proceeds from the sale of property and equipment to a related party		0.0
Decrease (increase) in restricted cash	0.0	0.0	(1.0)
Net principal decrease (increase) of other mortgage loans and real estate owned	19.7	(8.9)	(5.6)
Proceeds from sale (purchases) of debt securities collateralized by residential real estate	0.0	0.0
Intercompany advances	0.0	0.0	0.0
Payments related to acquisition of a business	0.0	0.0	0.0
Net cash used in investing activities	(27.4)	(15.7)	(14.9)
FINANCING ACTIVITIES
Proceeds from Notes Payable		118.7	120.6
Repayments of Notes Payable	(4.9)	(17.4)	(0.1)
Intercompany advances	111.4	48.9	11.8
Proceeds from stock associated with certain employee benefit plans	0.0	0.0	0.0
Income tax benefit from stock option exercises	0.0	0.0	0.0
Cash dividends paid	(61.8)	(31.6)	(52.6)
Net cash provided by (used in) financing activities	44.7	118.6	79.7
Increase (decrease) in cash and cash equivalents	1.3	(3.4)	7.3
Cash and cash equivalents at beginning of year	71.5	74.9	67.6
Cash and cash equivalents at end of year	$ 72.8	$ 71.5	$ 74.9