Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Cash Flows from Operating Activities
Net earnings (loss)	$ (568,000)	$ 85,398,000	$ (20,368,000)
Depreciation and amortization	218,601,000	234,728,000	256,606,000
Amortization of mortgage procurement costs	11,812,000	11,484,000	13,653,000
Impairment of real estate	119,324,000	4,763,000	8,907,000
Impairment of unconsolidated entities	82,186,000	72,459,000	36,356,000
Write-off of abandoned development projects	8,838,000	9,195,000	20,739,000
(Gain) loss on extinguishment of debt	(9,590,000)	21,035,000	(36,569,000)
Net gain on disposition of partial interests in rental properties and other investment	(17,665,000)	(257,990,000)
Deferred income tax expense (benefit)	(55,044,000)	69,524,000	(17,787,000)
Equity in earnings of unconsolidated entities	(21,147,000)	(42,265,000)	(21,303,000)
Stock-based compensation expense	7,650,000	7,969,000	7,509,000
Amortization and mark-to-market adjustments of derivative instruments	2,279,000	3,606,000	4,106,000
Non-cash interest expense related to Puttable Equity-Linked Senior Notes	1,737,000	1,858,000	6,917,000
Cash distributions from operations of unconsolidated entities	59,399,000	46,802,000	39,770,000
Cost of sales of land included in projects under construction and development and completed rental properties	10,820,000	18,490,000	35,607,000
Increase in land held for development and sale	(11,860,000)	(14,973,000)	(6,861,000)
Decrease in notes and accounts receivable	3,575,000	7,595,000	12,912,000
(Increase) Decrease in other assets	(11,433,000)	15,415,000	15,566,000
Increase in restricted cash and escrowed funds used for operating purposes	(4,354,000)	(31,701,000)	(4,917,000)
Increase (decrease) in accounts payable, accrued expenses and other liabilities	15,863,000	(26,899,000)	41,321,000
Net cash provided by operating activities	298,763,000	267,247,000	420,329,000
Cash Flows from Investing Activities
Capital expenditures	(760,381,000)	(723,158,000)	(942,609,000)
Payment of lease procurement costs	(22,907,000)	(20,387,000)	(13,153,000)
(Increase) decrease in other assets	(14,489,000)	(57,226,000)	2,373,000
Decrease (increase) in restricted cash and escrowed funds used for investing purposes	90,157,000	(249,024,000)	(132,329,000)
Proceeds from disposition of full or partial interests in rental properties and other investments	353,243,000	191,345,000	13,086,000
(Increase) decrease in investments in and advances to unconsolidated entities	(85,820,000)	11,401,000	(81,314,000)
Net cash used in investing activities	(440,197,000)	(847,049,000)	(1,153,946,000)
Cash Flows from Financing Activities
Proceeds from nonrecourse mortgage debt and notes payable	695,449,000	658,833,000	770,972,000
Principal payments on nonrecourse mortgage debt and notes payable	(572,584,000)	(321,629,000)	(260,294,000)
Borrowings on bank revolving credit facility	464,575,000	876,052,000	844,000,000
Payments on bank revolving credit facility	(601,727,000)	(822,416,000)	(1,125,984,000)
Payment of Puttable Equity-Linked Senior Notes due 2011	(39,407,000)
Payment of subordinated debt			(20,400,000)
Payment of transaction costs related to exchanges of Convertible Senior Notes due 2016 for Class A common stock	(3,200,000)
Purchase of senior notes due 2011 and 2017		(16,569,000)
Proceeds received from partial termination of Convertible Senior Notes hedge		1,869,000
Proceeds from Puttable Equity-Linked Senior Notes due 2014, net of $2,803 of issuance costs and discount			29,764,000
Payment for Convertible Senior Notes hedge transaction			(15,900,000)
Payment of deferred financing costs	(14,923,000)	(36,745,000)	(32,756,000)
Change in restricted cash and escrowed funds and book overdrafts	(1,578,000)	(1,322,000)	(4,251,000)
Proceeds from issuance of Series A preferred stock, net of $5,544 of issuance costs		44,456,000
Payment for equity call hedge related to the issuance of Series A preferred stock		(17,556,000)
Dividends paid to preferred shareholders	(15,400,000)	(11,807,000)
Sale of common stock, net			329,917,000
Purchase of treasury stock	(1,670,000)	(786,000)	(133,000)
Exercise of stock options	195,000	2,621,000	128,000
Contributions from redeemable noncontrolling interest		181,909,000
Contributions from noncontrolling interests	6,087,000	5,636,000	21,831,000
Distributions to noncontrolling interests	(89,644,000)	(20,777,000)	(12,339,000)
Net cash provided by financing activities	165,548,000	521,769,000	717,717,000
Net increase (decrease) in cash and equivalents	24,114,000	(58,033,000)	(15,900,000)
Cash and equivalents at beginning of period	193,372,000	251,405,000	267,305,000
Cash and equivalents at end of period	217,486,000	193,372,000	251,405,000
Operating activities
Increase in land held for development and sale	(1,399,000)	(31,599,000)	(50,740,000)
Decrease in notes and accounts receivable	16,785,000	22,560,000	10,842,000
Decrease in other assets	155,458,000	80,953,000	46,620,000
Decrease (increase) in restricted cash and escrowed funds	149,586,000	(1,953,000)	(142,000)
Increase (decrease) in accounts payable, accrued expenses and other liabilities	14,188,000	(111,940,000)	(97,233,000)
Total effect on operating activities	334,618,000	(41,979,000)	(90,653,000)
Investing activities
Decrease in projects under construction and development	429,690,000	32,816,000	108,000,000
Decrease in completed rental properties	1,230,710,000	667,495,000	68,003,000
(Increase) decrease in investments in and advances to unconsolidated entities	(298,492,000)	111,644,000	12,789,000
Total effect on investing activities	1,361,908,000	811,955,000	188,792,000
Financing activities
Decrease in nonrecourse mortgage debt and notes payable	(1,648,245,000)	(776,588,000)	(112,379,000)
(Decrease) increase in senior and subordinated debt	(40,000,000)	(277,658,000)	11,414,000
Decrease in deferred tax liability			(6,218,000)
Increase in preferred stock		170,000,000
Increase in class A common stock	959,000	2,636,000
Increase in additional paid-in capital	36,904,000	102,939,000	7,427,000
Increase in redeemable noncontrolling interest	6,887,000	46,845,000
(Decrease) increase in noncontrolling interest	(53,031,000)	(38,150,000)	1,617,000
Total effect on financing activities	(1,696,526,000)	(769,976,000)	(98,139,000)
Convertible Senior Notes due 2018
Cash Flows from Financing Activities
Proceeds from issuance of Convertible Senior Notes due 2018 and 2016, net of $10,625 and $6,838 of issuance costs respectively	339,375,000
Convertible senior notes due 2016
Cash Flows from Financing Activities
Proceeds from issuance of Convertible Senior Notes due 2018 and 2016, net of $10,625 and $6,838 of issuance costs respectively			193,162,000
Segment Discontinued Operations
Cash Flows from Operating Activities
Depreciation and amortization	4,339,000	13,289,000	12,149,000
Amortization of mortgage procurement costs	762,000	2,127,000	371,000
Impairment of real estate	10,257,000	81,643,000	27,394,000
Write-off of abandoned development projects			676,000
Deferred income tax expense (benefit)	6,536,000	(15,002,000)	(6,705,000)
Gain on disposition of rental properties and Lumber Group	$ (133,554,000)	$ (51,303,000)	$ (5,720,000)