Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Gross profit:
Income before income taxes	$ 318.1	$ 241.3
Income tax expense	111.2	83.6
Net income	206.9	157.7
Other comprehensive income, net of income tax:
Comprehensive income	$ 206.9	$ 158.9
Basic net income per common share (in dollars per share)	$ 0.55	$ 0.43
Net income per common share assuming dilution (in dollars per share)	0.55	0.42
Cash dividends declared per common share (in dollars per share)	$ 0.1	$ 0.08
Debt Securities [Member]
Other comprehensive income, net of income tax:
Net change in unrealized gain	$ 0.0	$ 1.2
Homebuilding [Member]
Revenues:
Home sales	2,797.7	2,340.9
Land/lot sales and other	28.4	20.2
Total revenues	2,826.1	2,361.1
Cost of sales:
Home sales	2,244.8	1,874.3
Land/lot sales and other	20.8	15.9
Inventory and land option charges	2.3	2.0
Total cost of sales	2,267.9	1,892.2
Gross profit:
Home sales	552.9	466.6
Land/lot sales and other	7.6	4.3
Inventory and land option charges	(2.3)	(2.0)
Total gross profit	558.2	468.9
Selling, general and administrative expense	268.4	241.7
Other (income) expense	(4.1)	(1.7)
Income before income taxes	293.9	228.9
Financial Services and Other [Member]
Gross profit:
Revenues	78.1	55.3
General and administrative expense	57.5	47.7
Interest and other (income) expense	(3.6)	(4.8)
Income before income taxes	$ 24.2	$ 12.4