Supplemental Guarantor Information - Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
OPERATING ACTIVITIES
Net cash provided by (used in) operating activities				$ 80.7	$ 306.5
INVESTING ACTIVITIES
Expenditures for property and equipment				(105.3)	(54.0)
Proceeds from sale of assets				143.8	261.1
Expenditures related to multi-family rental properties				(56.3)	(56.1)
Return of investment in unconsolidated entities				4.4	15.4
Net principal increase of other mortgage loans and real estate owned				(2.0)	(0.8)
Intercompany advances				0.0	0.0
Payments related to business acquisitions				310.9	158.1
Net cash (used in) provided by investing activities				(326.3)	7.5
FINANCING ACTIVITIES
Proceeds from notes payable				2,528.2	2,164.3
Repayment of notes payable				(2,536.1)	(2,179.5)
Advances (payments) on mortgage repurchase facility, net				158.8	106.3
Intercompany advances				0.0	0.0
Proceeds from stock associated with certain employee benefit plans				26.8	36.2
Cash paid for shares withheld for taxes	$ (15.4)	$ (4.1)	$ (10.3)	(19.5)	(10.3)
Cash dividends paid				(167.9)	(141.3)
Repurchases of common stock				(361.5)	(74.9)
Distributions to noncontrolling interests, net				(3.9)	(2.2)
Net cash (used in) provided by financing activities				(375.1)	(101.4)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				(620.7)	212.6
Cash, cash equivalents and restricted cash at beginning of period		1,506.0	1,024.3	1,506.0	1,024.3
Cash, cash equivalents and restricted cash at end of period				885.3	1,236.9
Eliminations [Member]
OPERATING ACTIVITIES
Net cash provided by (used in) operating activities				(78.7)	(62.0)
INVESTING ACTIVITIES
Expenditures for property and equipment				0.0	0.0
Proceeds from sale of assets				0.0	0.0
Expenditures related to multi-family rental properties				0.0	5.0
Return of investment in unconsolidated entities				0.0	0.0
Net principal increase of other mortgage loans and real estate owned				0.0	0.0
Intercompany advances				(497.0)	(615.7)
Payments related to business acquisitions				0.0	0.0
Net cash (used in) provided by investing activities				(497.0)	(610.7)
FINANCING ACTIVITIES
Proceeds from notes payable				0.0	0.0
Repayment of notes payable				0.0	0.0
Advances (payments) on mortgage repurchase facility, net				0.0	0.0
Intercompany advances				497.0	615.7
Proceeds from stock associated with certain employee benefit plans				0.0	0.0
Cash paid for shares withheld for taxes				0.0	0.0
Cash dividends paid				78.7	57.0
Repurchases of common stock				0.0	0.0
Distributions to noncontrolling interests, net				0.0	0.0
Net cash (used in) provided by financing activities				575.7	672.7
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				0.0	0.0
Cash, cash equivalents and restricted cash at beginning of period		0.0	0.0	0.0	0.0
Cash, cash equivalents and restricted cash at end of period				0.0	0.0
D.R. Horton, Inc. [Member]
OPERATING ACTIVITIES
Net cash provided by (used in) operating activities				210.9	(17.9)
INVESTING ACTIVITIES
Expenditures for property and equipment				(37.9)	(29.1)
Proceeds from sale of assets				10.4	0.0
Expenditures related to multi-family rental properties				0.0	0.0
Return of investment in unconsolidated entities				0.0	0.0
Net principal increase of other mortgage loans and real estate owned				0.0	0.0
Intercompany advances				497.0	615.7
Payments related to business acquisitions				302.6	560.0
Net cash (used in) provided by investing activities				166.9	26.6
FINANCING ACTIVITIES
Proceeds from notes payable				2,100.0	2,162.2
Repayment of notes payable				(2,450.0)	(2,165.2)
Advances (payments) on mortgage repurchase facility, net				0.0	0.0
Intercompany advances				0.0	0.0
Proceeds from stock associated with certain employee benefit plans				26.8	36.2
Cash paid for shares withheld for taxes				(19.5)	(10.3)
Cash dividends paid				(167.9)	(141.3)
Repurchases of common stock				(361.5)	(74.9)
Distributions to noncontrolling interests, net				0.0	0.0
Net cash (used in) provided by financing activities				(872.1)	(193.3)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				(494.3)	(184.6)
Cash, cash equivalents and restricted cash at beginning of period		914.7	788.7	914.7	788.7
Cash, cash equivalents and restricted cash at end of period				420.4	604.1
Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES
Net cash provided by (used in) operating activities				467.4	640.4
INVESTING ACTIVITIES
Expenditures for property and equipment				(22.6)	(21.5)
Proceeds from sale of assets				0.0	0.0
Expenditures related to multi-family rental properties				0.0	0.0
Return of investment in unconsolidated entities				0.0	0.0
Net principal increase of other mortgage loans and real estate owned				0.0	0.0
Intercompany advances				0.0	0.0
Payments related to business acquisitions				0.0	0.0
Net cash (used in) provided by investing activities				(22.6)	(21.5)
FINANCING ACTIVITIES
Proceeds from notes payable				0.0	0.0
Repayment of notes payable				(1.1)	(3.7)
Advances (payments) on mortgage repurchase facility, net				0.0	0.0
Intercompany advances				(487.0)	(660.6)
Proceeds from stock associated with certain employee benefit plans				0.0	0.0
Cash paid for shares withheld for taxes				0.0	0.0
Cash dividends paid				0.0	0.0
Repurchases of common stock				0.0	0.0
Distributions to noncontrolling interests, net				0.0	0.0
Net cash (used in) provided by financing activities				(488.1)	(664.3)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				(43.3)	(45.4)
Cash, cash equivalents and restricted cash at beginning of period		160.7	156.0	160.7	156.0
Cash, cash equivalents and restricted cash at end of period				117.4	110.6
Non-Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES
Net cash provided by (used in) operating activities				(518.9)	(254.0)
INVESTING ACTIVITIES
Expenditures for property and equipment				(44.8)	(3.4)
Proceeds from sale of assets				133.4	261.1
Expenditures related to multi-family rental properties				(56.3)	(61.1)
Return of investment in unconsolidated entities				4.4	15.4
Net principal increase of other mortgage loans and real estate owned				(2.0)	(0.8)
Intercompany advances				0.0	0.0
Payments related to business acquisitions				8.3	401.9
Net cash (used in) provided by investing activities				26.4	613.1
FINANCING ACTIVITIES
Proceeds from notes payable				428.2	2.1
Repayment of notes payable				(85.0)	(10.6)
Advances (payments) on mortgage repurchase facility, net				158.8	106.3
Intercompany advances				(10.0)	44.9
Proceeds from stock associated with certain employee benefit plans				0.0	0.0
Cash paid for shares withheld for taxes				0.0	0.0
Cash dividends paid				(78.7)	(57.0)
Repurchases of common stock				0.0	0.0
Distributions to noncontrolling interests, net				(3.9)	(2.2)
Net cash (used in) provided by financing activities				409.4	83.5
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				(83.1)	442.6
Cash, cash equivalents and restricted cash at beginning of period		$ 430.6	$ 79.6	430.6	79.6
Cash, cash equivalents and restricted cash at end of period				$ 347.5	$ 522.2