Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
OPERATING ACTIVITIES
Net income (loss)	$ (1,018)	$ 3,134
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation and amortization	25,868	24,732
Stock-based compensation	1,848	932
Straight-line rent receivable	(1,680)	(1,900)
Straight-line rent liability	102	90
Gain on sales of real estate properties	0	(3,428)
Impairments	3,630	4,170
Provision for bad debt, net of recoveries	(12)	(42)
Changes in operating assets and liabilities:
Other assets	(1,736)	1,290
Accounts payable and accrued liabilities	(21,485)	(20,628)
Other liabilities	(2,384)	2,587
Net cash provided by operating activities	3,133	10,937
INVESTING ACTIVITIES
Acquisition of real estate	(16,967)	(22,503)
Development of real estate	0	(4,400)
Tenant improvements and capital additions	(8,001)	(17,559)
Funding of mortgages	(24,304)	(12,642)
Proceeds from sales of real estate	1,112	6,624
Proceeds from mortgage repayment by previously consolidated VIE	0	35,057
Proceeds from mortgages and notes receivable repayments	39	4,725
Net cash used in investing activities	(48,121)	(10,698)
FINANCING ACTIVITIES
Net borrowings (repayments) on unsecured credit facility	(110,000)	26,000
Borrowings on notes and bonds payable	247,948	0
Repayments on notes and bonds payable	(16,110)	(1,213)
Dividends paid	(26,746)	(23,387)
Net proceeds from issuance of common stock	40,424	281
Common stock redemptions	(156)	(45)
Capital contributions received from noncontrolling interest holders	1,373	0
Distributions to noncontrolling interest holders	(29)	0
Debt issuance and assumption costs	(4,321)	(3)
Net cash provided by financing activities	132,383	1,633
Increase in cash and cash equivalents	87,395	1,872
Cash and cash equivalents, beginning of period	6,776	4,738
Cash and cash equivalents, end of period	94,171	6,610
Supplemental Cash Flow Information:
Interest paid	26,271	26,389
Capitalized interest	107	1,835
Company-financed real estate property sales	3,666	7,450
Invoices accrued for construction, tenant improvement and other capitalized costs	5,049	7,129
Construction liabilities transferred upon deconsolidation of VIE	$ 0	$ 3,450