Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 103,384	$ 88,816
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	69,238	52,918
Amortization of deferred financing costs	4,198	5,016
Loss on extinguishment of debt related to portfolio acquisition	9,153
Non-cash interest expense related to amortization of discount on exchangeable senior notes	947	444
Non-cash interest expense related to amortization of premium on notes payable	(983)	(951)
Compensation expense related to stock-based awards	3,654	3,318
Gain on purchase of joint venture partners' interests	(2,556)	(13,499)
Distributions from unconsolidated real estate ventures in excess of earnings	3,538	1,642
Changes in operating assets and liabilities:
Receivables from related parties and affiliated real estate joint ventures	891	7,587
Other assets, net	(1,303)	4,866
Accounts payable and accrued expenses	5,949	4,530
Other liabilities	2,474	(1,726)
Net cash provided by operating activities	198,584	152,961
Cash flows from investing activities:
Acquisition, development and redevelopment of real estate assets	(86,890)	(368,753)
Proceeds from sale of real estate assets	889
Investments in unconsolidated real estate ventures	(1,126)	(1,053)
Return of investment in unconsolidated real estate ventures		1,848
Change in restricted cash	(5,827)	2,384
Issuance of notes receivable	(5,000)	(7,875)
Purchase of equipment and fixtures	(2,349)	(1,620)
Net cash used in investing activities	(100,303)	(375,069)
Cash flows from financing activities:
Proceeds from the sale of common stock, net of offering costs		226,692
Net proceeds from issuance of exchangeable senior notes	246,250
Repurchase of exchangeable senior notes		(87,663)
Proceeds from notes payable and lines of credit	364,855	640,655
Principal payments on notes payable and lines of credit, including defeasance	(532,348)	(473,349)
Deferred financing costs	(6,135)	(8,427)
Redemption of Operating Partnership units held by noncontrolling interest	(41)	(155)
Net proceeds from exercise of stock options	5,876	8,931
Dividends paid on common stock	(116,712)	(60,693)
Distributions to noncontrolling interests	(9,112)	(6,759)
Net cash provided by (used in) financing activities	(47,367)	239,232
Net increase in cash and cash equivalents	50,914	17,124
Cash and cash equivalents, beginning of the period	30,785	26,484
Cash and cash equivalents, end of the period	81,699	43,608
Supplemental schedule of cash flow information
Interest paid	46,360	47,816
Income taxes paid	1,626	473
Tax effect from vesting of restricted stock grants and stock option exercises:
Other assets	3,147	3,099
Paid-in capital	(3,147)	(3,099)
Acquisitions of real estate assets
Real estate assets, net	210,372	148,021
Notes payable assumed	(7,122)	(147,592)
Notes payable assumed and immediately defeased	(98,960)
Value of Operating Partnership units issued	(102,039)	(429)
Receivables from related parties and affiliated real estate joint ventures	(2,251)
Receivable from sale of interest in real estate ventures
Other assets		3,349
Investments in unconsolidated real estate ventures		$ (3,349)