Supplemental Guarantor Information - Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Financial Services [Abstract]
Income before income taxes	$ 353.9	$ 300.5	$ 672.1	$ 541.8
Income tax expense	124.7	105.4	236.0	189.0
Net income	229.2	195.1	436.1	352.8
Comprehensive income	229.2	192.5	436.1	351.4
Eliminations [Member]
Financial Services [Abstract]
Income before income taxes	(279.6)	(244.4)	(534.9)	(445.1)
Income tax expense	(98.6)	(85.8)	(188.1)	(154.6)
Net income	(181.0)	(158.6)	(346.8)	(290.5)
Comprehensive income	(181.0)	(158.6)	(346.8)	(290.5)
D.R. Horton, Inc. [Member]
Financial Services [Abstract]
Income before income taxes	353.9	300.5	672.1	544.3
Income tax expense	124.7	105.4	236.0	189.0
Net income	229.2	195.1	436.1	355.3
Comprehensive income	229.2	192.5	436.1	353.9
Guarantor Subsidiaries [Member]
Financial Services [Abstract]
Income before income taxes	248.7	218.7	476.7	407.3
Income tax expense	87.1	76.4	166.4	141.5
Net income	161.6	142.3	310.3	265.8
Comprehensive income	161.6	142.3	310.3	265.8
Non-Guarantor Subsidiaries [Member]
Financial Services [Abstract]
Income before income taxes	30.9	25.7	58.2	35.3
Income tax expense	11.5	9.4	21.7	13.1
Net income	19.4	16.3	36.5	22.2
Comprehensive income	19.4	16.3	36.5	22.2
Homebuilding [Member]
Homebuilding:
Revenues	3,164.4	2,701.0	5,990.5	5,062.1
Cost of sales	2,549.9	2,169.3	4,817.8	4,061.4
Total gross profit	614.5	531.7	1,172.7	1,000.7
Selling, general and administrative expense	294.5	257.4	562.9	499.1
Equity in (income) of subsidiaries	0.0	0.0	0.0	0.0
Other (income) expense	(2.4)	(7.6)	(6.5)	(9.3)
Financial Services [Abstract]
Income before income taxes	322.4	281.9	616.3	510.9
Homebuilding [Member] \| Eliminations [Member]
Homebuilding:
Revenues	0.0	0.0	0.0	(5.4)
Cost of sales	0.0	0.0	0.0	(2.9)
Total gross profit	0.0	0.0	0.0	(2.5)
Selling, general and administrative expense	0.0	0.0	0.0	0.0
Equity in (income) of subsidiaries	279.6	244.4	534.9	442.6
Other (income) expense	0.0	0.0	0.0	0.0
Financial Services [Abstract]
Income before income taxes	(279.6)	(244.4)	(534.9)	(445.1)
Homebuilding [Member] \| D.R. Horton, Inc. [Member]
Homebuilding:
Revenues	1,094.4	864.4	2,012.5	1,660.0
Cost of sales	877.9	694.9	1,613.3	1,333.7
Total gross profit	216.5	169.5	399.2	326.3
Selling, general and administrative expense	143.3	118.8	267.2	230.8
Equity in (income) of subsidiaries	(279.6)	(244.4)	(534.9)	(442.6)
Other (income) expense	(1.1)	(5.4)	(5.2)	(6.2)
Financial Services [Abstract]
Income before income taxes	353.9	300.5	672.1	544.3
Homebuilding [Member] \| Guarantor Subsidiaries [Member]
Homebuilding:
Revenues	2,044.6	1,836.6	3,940.7	3,407.5
Cost of sales	1,647.3	1,482.3	3,172.0	2,736.1
Total gross profit	397.3	354.3	768.7	671.4
Selling, general and administrative expense	149.5	137.7	292.9	266.9
Equity in (income) of subsidiaries	0.0	0.0	0.0	0.0
Other (income) expense	(0.9)	(2.1)	(0.9)	(2.8)
Financial Services [Abstract]
Income before income taxes	248.7	218.7	476.7	407.3
Homebuilding [Member] \| Non-Guarantor Subsidiaries [Member]
Homebuilding:
Revenues	25.4	0.0	37.3	0.0
Cost of sales	24.7	(7.9)	32.5	(5.5)
Total gross profit	0.7	7.9	4.8	5.5
Selling, general and administrative expense	1.7	0.9	2.8	1.4
Equity in (income) of subsidiaries	0.0	0.0	0.0	0.0
Other (income) expense	(0.4)	(0.1)	(0.4)	(0.3)
Financial Services [Abstract]
Income before income taxes	(0.6)	7.1	2.4	4.4
Financial Services and Other [Member]
Financial Services [Abstract]
Revenues	86.9	66.9	165.0	122.2
General and administrative expense	60.7	51.8	118.1	99.6
Interest and other (income) expense	(5.3)	(3.5)	(8.9)	(8.3)
Income before income taxes	31.5	18.6	55.8	30.9
Financial Services and Other [Member] \| Eliminations [Member]
Financial Services [Abstract]
Revenues	0.0	0.0	0.0	0.0
General and administrative expense	0.0	0.0	0.0	0.0
Interest and other (income) expense	0.0	0.0	0.0	0.0
Income before income taxes	0.0	0.0	0.0	0.0
Financial Services and Other [Member] \| D.R. Horton, Inc. [Member]
Financial Services [Abstract]
Revenues	0.0	0.0	0.0	0.0
General and administrative expense	0.0	0.0	0.0	0.0
Interest and other (income) expense	0.0	0.0	0.0	0.0
Income before income taxes	0.0	0.0	0.0	0.0
Financial Services and Other [Member] \| Guarantor Subsidiaries [Member]
Financial Services [Abstract]
Revenues	0.0	0.0	0.0	0.0
General and administrative expense	0.0	0.0	0.0	0.0
Interest and other (income) expense	0.0	0.0	0.0	0.0
Income before income taxes	0.0	0.0	0.0	0.0
Financial Services and Other [Member] \| Non-Guarantor Subsidiaries [Member]
Financial Services [Abstract]
Revenues	86.9	66.9	165.0	122.2
General and administrative expense	60.7	51.8	118.1	99.6
Interest and other (income) expense	(5.3)	(3.5)	(8.9)	(8.3)
Income before income taxes	$ 31.5	$ 18.6	$ 55.8	$ 30.9

Financial services.

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Home building.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

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The aggregate financial services revenue and operating interest income earned during the reporting period.

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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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