Notes Payable (Details Textual) (USD $)	3 Months Ended					6 Months Ended					1 Months Ended			1 Months Ended								3 Months Ended		6 Months Ended
	Mar. 31, 2013	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Letter of Credit One [Member]	Mar. 31, 2013 2% convertible senior notes [Member]	Sep. 30, 2012 2% convertible senior notes [Member]	Jul. 25, 2012 Homebuilding [Member]	Mar. 31, 2013 Homebuilding [Member]	Sep. 30, 2012 Homebuilding [Member]	Sep. 30, 2012 Homebuilding [Member] Line of Credit [Member]	Mar. 31, 2013 Homebuilding [Member] Senior Note Twenty Six [Member]	Jan. 31, 2013 Homebuilding [Member] Senior Note Twenty Six [Member]	Mar. 31, 2013 Homebuilding [Member] Senior Note Twenty Seven [Member]	Jan. 31, 2013 Homebuilding [Member] Senior Note Twenty Seven [Member]	Mar. 31, 2013 Financial Services [Member]	Dec. 31, 2012 Financial Services [Member]	Sep. 30, 2012 Financial Services [Member]	Mar. 31, 2013 Financial Services [Member] Minimum [Member]	Mar. 31, 2013 Financial Services [Member] Maximum [Member]	Mar. 31, 2013 Dividend Declared [Member]	Mar. 31, 2013 Accelerated Dividend [Member]
Debt Instrument [Line Items]
Repurchase Of Purchased Loans Specified Time Frame																						45 days	120 days
Line of Credit Facility, Term														5 years
Notes Payable [Abstract]
Base capacity of mortgage repurchase facility												$ 600,000,000							$ 300,000,000	$ 180,000,000
Maximum capacity of mortgage repurchase facility												1,000,000,000							400,000,000
Letter of Credit, Maximum Borrowing Capacity												300,000,000
Line of Credit Facility, Amount Outstanding												0	0
Letters of Credit Outstanding, Amount	48,800,000					48,800,000		41,200,000
Cash dividends declared per common share (in dollars per share)	$ 0.0000	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.1875	$ 0.0750																	$ 0.0375	$ 0.15
Debt Conversion, Converted Instrument, Shares Issued		76.5697				77.18004
Principal amount									1,000							400,000,000		300,000,000
Debt Instrument, Interest Rate, Effective Percentage															3.80%		4.90%
Debt Instrument, Convertible, Conversion Price									$ 12.96	$ 13.06
Incremental Common Shares Attributable to Conversion of Debt Securities	38,600,000			0		38,600,000	0
Authorized repurchase of debt securities											500,000,000
Debt repurchase program, remaining authorized repurchase amount												500,000,000
Mortgage loans held for sale pledged under repurchase agreement																			373,300,000
Mortgage loans, collateral value																			347,900,000
Advance pay downs on mortgage repurchase facility																			102,100,000
Mortgage repurchase facility																			$ 245,800,000		$ 187,800,000
Interest rate on mortgage repurchase facility																			2.75%