CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
OPERATING ACTIVITIES
Net income	$ 33,225	$ 32,887	$ 22,834
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization from continuing operations	65,789	61,345	56,739
Depreciation and amortization from discontinued operations	130	929	712
Stock-based compensation expense	4,229	3,497	2,452
Gain on sales of land and real estate investments	(822)	(6,510)	(36)
Changes in operating assets and liabilities:
Accrued income and other assets	(1,629)	601	(1,425)
Accounts payable, accrued expenses and prepaid rent	8,906	(1,118)	5,466
Other	(78)	177	(195)
NET CASH PROVIDED BY OPERATING ACTIVITIES	109,750	91,808	86,547
INVESTING ACTIVITIES
Real estate development	(76,240)	(55,404)	(42,148)
Purchases of real estate	(72,397)	(51,750)	(88,592)
Real estate improvements	(20,807)	(18,135)	(19,048)
Proceeds from sales of real estate investments	4,273	17,087	0
Advances on mortgage loans receivable	0	(5,223)	0
Repayments on mortgage loans receivable	463	20	33
Changes in accrued development costs	509	1,242	5,255
Changes in other assets and other liabilities	(11,912)	(7,745)	(6,333)
NET CASH USED IN INVESTING ACTIVITIES	(176,111)	(119,908)	(150,833)
FINANCING ACTIVITIES
Proceeds from unsecured bank credit facilities	424,375	284,877	336,575
Repayments on unsecured bank credit facilities	(411,583)	(363,233)	(273,353)
Proceeds from secured debt	0	54,000	65,000
Repayments on secured debt	(107,953)	(74,308)	(81,128)
Proceeds from unsecured debt	175,000	80,000	50,000
Debt issuance costs	(2,222)	(1,490)	(925)
Distributions paid to stockholders (not including dividends accrued on unvested restricted stock)	(64,798)	(61,297)	(56,042)
Proceeds from common stock offerings	53,247	109,588	25,181
Proceeds from exercise of stock options	120	108	217
Proceeds from dividend reinvestment plan	206	219	249
Other	(1,281)	720	(1,451)
NET CASH PROVIDED BY FINANCING ACTIVITIES	65,111	29,184	64,323
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(1,250)	1,084	37
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	1,258	174	137
CASH AND CASH EQUIVALENTS AT END OF YEAR	8	1,258	174
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest, net of amount capitalized of $5,064, $4,660 and $3,771 for 2013, 2012 and 2011, respectively	$ 32,880	$ 34,385	$ 33,671