Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
OPERATING ACTIVITIES
Net income (loss)	$ 3,963	$ (1,018)
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation and amortization	28,049	25,868
Stock-based compensation	1,516	1,848
Straight-line rent receivable	(2,303)	(1,680)
Straight-line rent liability	108	102
Impairments	3,425	3,630
Provision for bad debt, net of recoveries	47	(12)
Changes in operating assets and liabilities:
Other assets	(3,087)	(1,736)
Accounts payable and accrued liabilities	(21,577)	(21,485)
Other liabilities	(1,848)	(2,384)
Net cash provided by operating activities	8,293	3,133
INVESTING ACTIVITIES
Acquisitions of real estate	0	(16,967)
Additional long-lived assets	(15,882)	(8,001)
Funding of mortgages	(798)	(24,304)
Proceeds from acquisition of real estate upon mortgage note receivable default	204	0
Proceeds from sales of real estate	0	1,112
Proceeds from mortgages and notes receivable repayments	4	39
Net cash used in investing activities	(16,472)	(48,121)
FINANCING ACTIVITIES
Net borrowings (repayments) on unsecured credit facility	(159,000)	(110,000)
Borrowings on term loan	200,000	0
Borrowings on notes and bonds payable	0	247,948
Repayments on notes and bonds payable	(1,462)	(16,110)
Dividends paid	(28,802)	(26,746)
Net proceeds from issuance of common stock	374	40,424
Common stock redemptions	(227)	(156)
Capital contributions received from noncontrolling interest holders	0	1,373
Distributions to noncontrolling interest holders	(32)	(29)
Debt issuance and assumption costs	(1,174)	(4,321)
Net cash provided by (used in) financing activities	9,677	132,383
Increase in cash and cash equivalents	1,498	87,395
Cash and cash equivalents, beginning of period	8,671	6,776
Cash and cash equivalents, end of period	10,169	94,171
Supplemental Cash Flow Information:
Interest paid	25,153	26,271
Capitalized interest	0	107
Company-financed real estate property sales	0	3,666
Invoices accrued for construction, tenant improvement and other capitalized costs	$ 6,988	$ 5,049