Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 33,931	$ 22,518
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	23,025	16,524
Amortization of deferred financing costs	1,510	2,246
Non-cash interest expense related to amortization of discount on exchangeable senior notes		444
Non-cash interest expense related to amortization of premium on notes payable	(565)	(316)
Compensation expense related to stock-based awards	1,023	957
Gain on purchase of joint venture partners' interest	(2,556)
Distributions from unconsolidated real estate ventures in excess of earnings	1,154	589
Changes in operating assets and liabilities:
Receivables from related parties and affiliated real estate joint ventures	(277)	3,102
Other assets	1,051	2,979
Accounts payable and accrued expenses	(6,864)	(5,250)
Other liabilities	(316)	(3,003)
Net cash provided by operating activities	51,116	40,790
Cash flows from investing activities:
Acquisition, development and redevelopment of real estate assets	(18,754)	(18,495)
Investments in unconsolidated real estate ventures	(589)	(356)
Return of investment in real estate ventures		1,492
Change in restricted cash	(3,181)	1,495
Purchase of equipment and fixtures	(821)	(531)
Net cash used in investing activities	(23,345)	(16,395)
Cash flows from financing activities:
Proceeds from notes payable and lines of credit	81,776	206,970
Principal payments on notes payable and lines of credit	(74,912)	(198,048)
Deferred financing costs	(1,340)	(3,418)
Redemption of Operating Partnership units held by noncontrolling interest	(20)
Net proceeds from exercise of stock options	1,635	2,444
Dividends paid on common stock	(27,730)	(19,002)
Distributions to noncontrolling interests	(2,390)	(2,250)
Net cash used in financing activities	(22,981)	(13,304)
Net increase in cash and cash equivalents	4,790	11,091
Cash and cash equivalents, beginning of the period	30,785	26,484
Cash and cash equivalents, end of the period	35,575	37,575
Supplemental schedule of cash flow information
Interest paid, net of amounts capitalized	15,909	14,705
Income taxes paid	589	473
Acquisitions of real estate assets
Real estate assets, net	2,251	377
Operating Partnership units issued		(377)
Receivables from related parties and affiliated real estate joint ventures	(2,251)
Sale of interest in unconsolidated real estate venture
Other assets		3,349
Investments in unconsolidated real estate ventures		$ (3,349)