Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 27,801	$ 24,989
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	28,441	26,961
In-place lease adjustment	(197)	72
Tenant improvement reimbursements net of lease incentives	(438)	(277)
Stock compensation	1,230	1,423
Decrease in receivables and other assets	943	2,425
Decrease in accrued and other liabilities	(2,452)	(3,067)
Total adjustments	27,527	27,537
Net cash provided by operating activities	55,328	52,526
Cash flows from investing activities:
Capital improvements to real estate facilities	(10,227)	(9,692)
Capital improvements to land and building held for development	(628)
Net cash used in investing activities	(10,855)	(9,692)
Cash flows from financing activities:
Repayment of borrowings on term loan debt		(110,000)
Principal payments on mortgage notes payable		(47)
Repayment of mortgage notes payable		(18,055)
Net proceeds from the issuance of preferred stock		106,311
Proceeds from the exercise of stock options	2,033	1,594
Distributions paid to preferred shareholders	(15,122)	(13,554)
Distributions paid to noncontrolling interests - common units	(3,653)	(3,214)
Distributions paid to common shareholders	(13,443)	(10,696)
Net cash used in financing activities	(30,185)	(47,661)
Net increase (decrease) in cash and cash equivalents	14,288	(4,827)
Cash and cash equivalents at the beginning of the period	31,481	12,883
Cash and cash equivalents at the end of the period	45,769	8,056
Adjustment to noncontrolling interests in underlying operating partnership:
Noncontrolling interests - common units	374	(407)
Paid-in capital	(374)	407
Accrued preferred stock distribution:
Accured and other liabilities		296
Cumulative distributions		(296)
Transfer to land and building held for development:
Land		(5,927)
Buildings and improvements		(10,270)
Accumulated depreciation		778
Land and building held for development		$ 15,419