Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 41,209	$ 33,931
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	28,375	23,025
Amortization of deferred financing costs	1,641	1,510
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	662
Non-cash interest expense related to amortization of premium on notes payable	(895)	(565)
Compensation expense related to stock-based awards	1,121	1,023
Gain on purchase of joint venture partners' interests		(2,556)
Distributions from unconsolidated real estate ventures in excess of earnings	1,024	1,154
Changes in operating assets and liabilities:
Receivables from related parties and affiliated real estate joint ventures	(1,424)	(277)
Other assets	1,448	1,051
Accounts payable and accrued expenses	(7,715)	(6,864)
Other liabilities	(874)	(316)
Net cash provided by operating activities	64,572	51,116
Cash flows from investing activities:
Acquisition, development and redevelopment of real estate assets	(256,759)	(18,754)
Investments in unconsolidated real estate ventures		(589)
Change in restricted cash	1,425	(3,181)
Purchase of equipment and fixtures	(1,274)	(821)
Net cash used in investing activities	(256,608)	(23,345)
Cash flows from financing activities:
Proceeds from notes payable and lines of credit	291,157	81,776
Principal payments on notes payable and lines of credit	(127,881)	(74,912)
Deferred financing costs	(1,392)	(1,340)
Redemption of Operating Partnership units held by noncontrolling interest		(20)
Net proceeds from exercise of stock options	1,056	1,635
Dividends paid on common stock	(46,347)	(27,730)
Distributions to noncontrolling interests	(4,265)	(2,390)
Net cash provided by (used in) financing activities	112,328	(22,981)
Net (decrease) increase in cash and cash equivalents	(79,708)	4,790
Cash and cash equivalents, beginning of the period	126,723	30,785
Cash and cash equivalents, end of the period	47,015	35,575
Supplemental schedule of cash flow information
Interest paid, net of amounts capitalized	16,445	15,909
Income taxes paid	1,244	589
Tax effect from vesting of restricted stock grants and option exercises
Other assets	1,262
Paid-in capital	(1,262)
Acquisitions of real estate assets
Real estate assets, net		2,251
Receivables from related parties and affiliated real estate joint ventures		$ (2,251)