Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
OPERATING ACTIVITIES
Net income (loss)	$ 9,974	$ (25,256)
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation and amortization	56,875	51,625
Stock-based compensation	2,782	2,985
Straight-line rent receivable	(4,816)	(3,492)
Straight-line rent liability	317	204
Gain on sales of real estate properties	(3)	(1,783)
Loss on extinguishment of debt	0	29,907
Impairments	6,529	3,630
Provision for bad debt, net of recoveries	128	7
Changes in operating assets and liabilities:
Other assets	(14,305)	(4,060)
Accounts payable and accrued liabilities	(5,308)	(8,806)
Other liabilities	(961)	(1,406)
Net cash provided by operating activities	51,212	43,555
INVESTING ACTIVITIES
Acquisitions of real estate	(20,003)	(34,591)
Additional long-lived assets	(36,171)	(34,305)
Funding of mortgages	(1,244)	(45,908)
Proceeds from acquisition of real estate upon mortgage note receivable default	204	0
Proceeds from sales of real estate	5,904	12,239
Proceeds from mortgages and notes receivable repayments	754	68
Net cash used in investing activities	(50,556)	(102,497)
FINANCING ACTIVITIES
Net borrowings (repayments) on unsecured credit facility	(149,000)	120,000
Borrowings on term loan	200,000	0
Borrowings on notes and bonds payable	0	247,948
Repayments on notes and bonds payable	(2,928)	(17,480)
Redemption of notes and bonds payable	0	(371,839)
Dividends paid	(57,660)	(54,061)
Net proceeds from issuance of common stock	27,873	132,416
Common stock redemptions	(382)	(246)
Capital contributions received from noncontrolling interest holders	0	1,388
Distributions to noncontrolling interest holders	(344)	(32)
Payments to Noncontrolling Interests	(8,189)	0
Debt issuance and assumption costs	(1,174)	(4,776)
Net cash provided by (used in) financing activities	8,196	53,318
Increase in cash and cash equivalents	8,852	(5,624)
Cash and cash equivalents, beginning of period	8,671	6,776
Cash and cash equivalents, end of period	17,523	1,152
Supplemental Cash Flow Information:
Interest paid	33,904	38,057
Capitalized interest	0	171
Company-financed real estate property sales	0	4,241
Invoices accrued for construction, tenant improvement and other capitalized costs	$ 12,648	$ 6,011