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	$ 32,887	$ 22,834	$ 18,755
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization from continuing operations	61,696	56,757	57,806
Depreciation and amortization from discontinued operations	578	694	544
Stock-based compensation expense	3,497	2,452	1,998
Gain on sales of land and real estate investments	(6,510)	(36)	0
Changes in operating assets and liabilities:
Accrued income and other assets	601	(1,425)	212
Accounts payable, accrued expenses and prepaid rent	(1,118)	5,466	(2,268)
Other	177	(195)	(189)
NET CASH PROVIDED BY OPERATING ACTIVITIES	91,808	86,547	76,858
INVESTING ACTIVITIES
Real estate development	(55,404)	(42,148)	(9,145)
Purchases of real estate	(51,750)	(88,592)	(23,906)
Real estate improvements	(18,135)	(19,048)	(23,720)
Proceeds from sales of real estate investments	17,087	0	0
Advances on mortgage loans receivable	(5,223)	0	0
Repayments on mortgage loans receivable	20	33	37
Changes in accrued development costs	1,242	5,255	8
NET CASH USED IN INVESTING ACTIVITIES	(7,745)	(6,333)	(6,775)
NET CASH USED IN INVESTING ACTIVITIES	(119,908)	(150,833)	(63,501)
FINANCING ACTIVITIES
Proceeds from bank borrowings	284,877	336,575	211,041
Repayments on bank borrowings	(363,233)	(273,353)	(208,903)
Proceeds from mortgage notes payable	54,000	65,000	74,000
Principal payments on mortgage notes payable	(74,308)	(81,128)	(32,401)
Proceeds from unsecured term loans payable	80,000	50,000	0
Debt issuance costs	(1,490)	(925)	(709)
Distributions paid to stockholders	(61,297)	(56,042)	(56,294)
Proceeds from common stock offerings	109,588	25,181	303
Proceeds from exercise of stock options	108	217	404
Proceeds from dividend reinvestment plan	219	249	262
Other	720	(1,451)	(1,985)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	29,184	64,323	(14,282)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	1,084	37	(925)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	174	137	1,062
CASH AND CASH EQUIVALENTS AT END OF YEAR	1,258	174	137
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest, net of amount capitalized of $4,660, $3,771 and $3,613 for 2012, 2011 and 2010, respectively	$ 34,385	$ 33,671	$ 34,380