Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
OPERATING ACTIVITIES
Net income	$ 51,601	$ 19,324	$ 2,174
Results from discontinued operations	(37,652)	(5,653)	(552)
Income from continuing operations	13,949	13,671	1,622
Adjustments to reconcile income from continuing operations to net cash provided by operating activities:
Deferred rent revenue and amortization of lease intangibles	(6,967)	(3,735)	1,080
Depreciation and amortization	61,853	55,936	34,419
Amortization of debt issuance costs and debt fair value adjustments	3,911	3,883	503
Early extinguishment of debt		25,867
Loan transfer and consent fees		8,808
Gain on acquisition of controlling interests		(46,371)	(4,297)
Stock-based compensation expense	2,852	2,615
Loss from real estate joint ventures		188	4,406
Distribution of earnings from real estate joint ventures			6,713
Other, net	2,422	2,666	800
Changes in operating assets and liabilities
Change in restricted cash	(1,000)	97	(74)
Change in accounts receivable	63	(3,570)	(19)
Change in prepaid expenses and other assets	143	(2,040)	(5,155)
Change in accounts payable and accrued expenses	(1,799)	2,128	3,206
Change in security deposits and other liabilities	136	(943)	(45)
Net cash provided by operating activities of continuing operations	75,563	59,200	43,159
Net cash provided by operating activities of discontinued operations	382	6,164	5,187
Net cash provided by operating activities	75,945	65,364	48,346
INVESTING ACTIVITIES
Acquisition of real estate, net of cash acquired	(273,990)	(231,558)	(32,962)
Capital expenditures	(34,582)	(10,777)	(3,929)
Change in restricted cash-reserves for capital improvements	2,557	(3,069)
Cash acquired from acquisition of controlling interests in real estate joint ventures		15,222
Leasing commissions	(3,456)	(2,444)	(1,536)
Purchase of marketable securities		(33,103)
Maturity of marketable securities	4,384	4,993
Sale of marketable securities	23,191
Distribution of capital from real estate joint ventures			10,607
Issuance of notes receivable to affiliate			(800)
Net cash used in investing activities of continuing operations	(281,896)	(260,736)	(28,620)
Net cash provided by (used in) investing activities of discontinued operations	87,601	29,047	(885)
Net cash used in investing activities	(194,295)	(231,689)	(29,505)
FINANCING ACTIVITIES
Issuance of secured notes payable	132,900	84,500	7,500
Repayment of secured notes payable	(34,626)	(264,250)	(12,873)
Defeasance costs on repayment of secured notes payable		(24,345)
Proceeds from unsecured line of credit	164,000
Repayment of unsecured line of credit	(164,000)
Loan transfer and consent fees paid		(8,350)
Issuance of unsecured notes payable			36,200
Repayment of unsecured notes payable		(38,013)	(11,051)
Repayment of notes payable to affiliates		(19,279)	(2,401)
Debt issuance costs	(1,355)	(2,961)	(436)
Proceeds from issuance of common stock, net		596,541
Proceeds from private placement of common units		5,410
Dividends paid to common stock and unitholders	(48,452)	(46,123)
Payments to nonaccredited investors		(6,075)
Deferred offering costs	(361)
Contributions from Predecessor's controlling and noncontrolling interests			7,665
Distributions to Predecessor's controlling and noncontrolling interests		(39,960)	(25,681)
Net cash provided by (used in) financing activities	48,106	237,095	(1,077)
Net (decrease) increase in cash and cash equivalents	(70,244)	70,770	17,764
Cash and cash equivalents, beginning of period	112,723	41,953	24,189
Cash and cash equivalents, end of period	$ 42,479	$ 112,723	$ 41,953