Consolidated Statements Of Income And Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Property revenues
Rental revenues	$ 626,127		$ 533,937		$ 488,895
Other property revenues	101,781		87,137		79,177
Total property revenues	727,908		621,074		568,072
Property expenses
Property operating and maintenance	196,811		175,000		163,628
Real estate taxes	72,858		65,128		63,150
Total property expenses	269,669		240,128		226,778
Non-property income
Fee and asset management	12,345		9,973		8,172
Interest and other income (loss)	(710)		4,649		8,584
Income on deferred compensation plans	4,772		6,773		11,581
Total non-property income	16,407		21,395		28,337
Other expenses
Property management	21,796		20,686		19,982
Fee and asset management	6,631		5,935		4,841
General and administrative	37,528		35,456		30,762
Interest	104,282		112,414		125,893
Depreciation and amortization	203,077		171,127		161,760
Amortization of deferred financing costs	3,608		5,877		4,102
Expense on deferred compensation plans	4,772		6,773		11,581
Total other expenses	381,694		358,268		358,921
Gain on acquisition of controlling interest in joint ventures	57,418		0		0
Gain on sale of properties, including land	0		4,748		236
Gain on sale of unconsolidated joint venture interests	0		1,136		0
Loss on discontinuation of hedging relationship	0		(29,791)		0
Impairment provision on a technology investment	0		0		(1,000)
Equity in income (loss) of joint ventures	20,175	[1]	5,679	[1]	(839)	[1]
Income from continuing operations before income taxes	170,545		25,845		9,107
Income tax expense - current	(1,208)		(2,220)		(1,581)
Income from continuing operations	169,337		23,625		7,526
Income from discontinued operations	9,495		11,715		14,002
Gain on sale of discontinued operations, net of tax	115,068		24,621		9,614
Net income	293,900		59,961		31,142
Less income allocated to non-controlling interests from continuing operations	(4,821)		(3,453)		(821)
Less income, including gain on sale, allocated to non-controlling interests from discontinued operations	(2,838)		(129)		(105)
Less income allocated to perpetual preferred units	(776)		(7,000)		(7,000)
Less write off of original issuance costs of redeemed perpetual preferred units	(2,075)		0		0
Net income attributable to common shareholders	283,390		49,379		23,216
Earnings per share - basic
Income (loss) from continuing operations attributable to common shareholders	$ 1.90		$ 0.17		$ (0.01)
Income from discontinued operations, including gain on sale, attributable to common shareholders	$ 1.45		$ 0.50		$ 0.34
Net income attributable to common shareholders, as adjusted - per share	$ 3.35		$ 0.67		$ 0.33
Earnings per share - diluted
Income (loss) from continuing operations attributable to common shareholders	$ 1.88		$ 0.17		$ (0.01)
Income from discontinued operations, including gain on sale, attributable to common shareholders	$ 1.42		$ 0.49		$ 0.34
Net income attributable to common shareholders, as adjusted - per share	$ 3.30		$ 0.66		$ 0.33
Weighted average number of common shares outstanding - basic	83,772		72,756		68,608
Weighted average number of common shares outstanding - diluted	85,556		73,462		68,608
Net income attributable to common shareholders
Income from continuing operations	169,337		23,625		7,526
Less income allocated to non-controlling interests from continuing operations	(4,821)		(3,453)		(821)
Less income allocated to perpetual preferred units	(776)		(7,000)		(7,000)
Less write off of original issuance costs of redeemed perpetual preferred units	(2,075)		0		0
Income (loss) from continuing operations attributable to common shareholders	161,665		13,172		(295)
Income from discontinued operations, including gain on sale	124,563		36,336		23,616
Less income, including gain on sale, allocated to non-controlling interests from discontinued operations	(2,838)		(129)		(105)
Income from discontinued operations, including gain on sale, attributable to common shareholders	121,725		36,207		23,511
Net income attributable to common shareholders	283,390		49,379		23,216
Condensed Consolidated Statements of Comprehensive Income:
Net income	293,900		59,961		31,142
Other comprehensive income
Unrealized loss on cash flow hedging activities	0		(2,692)		(19,059)
Reclassification of net losses on cash flow hedging activities	0		39,657		23,385
Unrealized gain on available-for-sale securities, net of tax	0		0		3,306
Reclassification of gain on available-for-sale investment to earnings, net of tax	0		(3,306)		0
Reclassification of prior service cost and net loss on post retirement obligations	30		0		0
Unrealized gain (loss) and unamortized prior service cost on postretirement obligation	(409)		(884)		65
Comprehensive income	293,521		92,736		38,839
Less income allocated to non-controlling interests from continuing operations	(4,821)		(3,453)		(821)
Less income, including gain on sale, allocated to non-controlling interests from discontinued operations	(2,838)		(129)		(105)
Less income allocated to perpetual preferred units	(776)		(7,000)		(7,000)
Less write off of original issuance costs of redeemed perpetual preferred units	(2,075)		0		0
Comprehensive income attributable to common shareholders	$ 283,011		$ 82,154		$ 30,913

[1] (3)Equity in income (loss) excludes our ownership interest of fee income from various property management services and interest income from mezzanine loans with our joint ventures.