Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
PROPERTIES:
Operating properties, net of accumulated depreciation of $348,142 and $324,543 in 2015 and 2014, respectively	$ 2,271,966	$ 2,181,684
Projects under development, net of accumulated depreciation of $202 in 2015	10,101	91,615
Land	20,971	21,646
Total properties	2,303,038	2,294,945
Cash and cash equivalents	4,388	0
Restricted cash	4,773	5,042
Notes and accounts receivable, net of allowance for doubtful accounts of $1,678 and $1,643 in 2015 and 2014, respectively	12,109	10,732
Deferred rents receivable	64,161	57,939
Investment in unconsolidated joint ventures	100,821	100,498
Intangible assets, net of accumulated amortization of $87,595 and $76,050 in 2015 and 2014, respectively	152,719	163,244
Other assets	42,652	34,930
Total assets	2,684,661	2,667,330
LIABILITIES AND EQUITY
Notes payable	847,948	792,344
Accounts payable and accrued expenses	51,102	76,240
Deferred income	22,822	23,277
Intangible liabilities, net of accumulated amortization of $19,605 and $16,897 in 2015 and 2014, respectively	67,313	70,020
Other liabilities	32,541	31,991
Total liabilities	1,021,726	993,872
STOCKHOLDERS' INVESTMENT:
Common stock, $1 par value, 350,000,000 and 250,000,000 shares authorized, 220,172,267 and 220,082,610 shares issued in 2015 and 2014, respectively	220,172	220,083
Additional paid-in capital	1,720,506	1,720,972
Treasury stock at cost, 3,570,082 shares in 2015 and 2014	(86,840)	(86,840)
Distributions in excess of cumulative net income	(190,903)	(180,757)
Total equity	1,662,935	1,673,458
Total liabilities and equity	$ 2,684,661	$ 2,667,330