Investments in Unconsolidated Entities (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013		Jan. 31, 2012		Jan. 31, 2011	Jan. 31, 2010
Real Estate
Completed rental properties	$ 8,631,542		$ 7,183,448
Projects under construction and development	1,326,703		2,328,979
Land held for development and sale	65,059		77,298
Total Real Estate	10,023,304		9,589,725
Less accumulated depreciation	(1,654,632)		(1,526,503)
Real Estate, net	8,368,672		8,063,222
Cash and equivalents	333,220		217,486		193,372	251,405
Other assets	614,592		608,541
Mortgage debt and notes payable, nonrecourse	5,740,660		5,659,523
Members' and partners' equity	637,341		945,129
Operations:
Operating expenses	(732,275)		(654,346)		(632,822)
Impairment of real estate	(30,660)		(235)		(4,763)
Depreciation and amortization	(229,661)		(208,801)		(225,082)
Interest and other income	45,915		52,094		52,792
Net loss on land held for divestiture activity	6,480		(115,654)		0
Gain on disposition of partial interest in a rental property	0		17,665		257,990
Discontinued operations:
Gain on disposition of rental properties	0		0		28,289
Discontinued operations subtotal	97,261		122,987		(23,120)
Impairment of investments in unconsolidated entities	(390)		(40,284)		(71,716)
Gain (loss) on disposition of equity method investments	16,107		12,567		(830)
Net earnings (loss) (pre-tax) from unconsolidated entities	44,631		(61,039)		(30,194)
Investments in Unconsolidated Entities (Textual) [Abstract]
Mortgage debt and notes payable, nonrecourse related to the land held by the unconsolidated entities	1,700		19,084
Equity Method Investee [Member]
Real Estate
Completed rental properties	7,317,652		7,287,539
Projects under construction and development	106,705		287,738
Land held for development and sale	89,268	[1]	224,224	[1]
Total Real Estate	7,513,625		7,799,501
Less accumulated depreciation	(1,413,510)		(1,257,091)
Real Estate, net	6,100,115		6,542,410
Cash and equivalents	120,545		149,702
Restricted cash - military housing bond funds	146,484		284,641
Other restricted cash and escrowed funds	319,989		274,201
Other assets	730,308		756,564
Total Assets	7,417,441		8,007,518
Mortgage debt and notes payable, nonrecourse	6,261,983	[2]	6,551,891	[2]
Other liabilities	518,117		510,498
Members' and partners' equity	637,341		945,129
Total Liabilities and Members' and Partners' Equity	7,417,441		8,007,518
Operations:
Revenues	1,161,122		1,037,006		905,524
Operating expenses	(652,651)		(558,094)		(517,899)
Interest expense including extinguishment of debt	(329,903)		(319,946)		(262,860)
Impairment of real estate	0		0		(1,457)
Depreciation and amortization	(217,664)		(197,299)		(162,153)
Interest and other income	17,694		14,800		15,779
Net loss on land held for divestiture activity	(102)		0		0
Gain on disposition of partial interest in a rental property	131,027		0		0
Gain (loss) from continuing operations	109,523		(23,533)		(23,066)
Discontinued operations:
Operating loss from rental properties	(4,970)		(9,990)		(6,079)
Gain on disposition of rental properties	0		0		28,289
Discontinued operations subtotal	(4,970)		(9,990)		22,210
Net earnings (loss) (pre-tax)	104,553		(33,523)		(856)
Company's portion of net earnings (pre-tax)	69,320		8,580		42,352
Impairment of investments in unconsolidated entities	(390)		(40,284)		(71,716)
Impairment of investments in unconsolidated entities with land held for divestiture	(40,406)		(41,902)		0
Gain (loss) on disposition of equity method investments	16,107		12,567		(830)
Net earnings (loss) (pre-tax) from unconsolidated entities	44,631		(61,039)		(30,194)
Investments in Unconsolidated Entities (Textual) [Abstract]
Land held by unconsolidated entities in which the Company is currently reviewing its options to divest its portion	89,268		181,749
Mortgage debt and notes payable, nonrecourse related to the land held by the unconsolidated entities	$ 18,638		$ 35,551

[1] The amounts at January 31, 2013 and 2012 include $89,268 and $181,749 of land held by unconsolidated entities in which the Company is currently reviewing its options to divest its portion of land held by these unconsolidated entities.

[2] The amounts at January 31, 2013 and 2012 include $18,638 and $35,551 of mortgage debt and notes payable, nonrecourse related to the land held by the unconsolidated entities discussed in footnote (1).