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	$ 180,226	$ 121,664	$ 115,266
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Gain on early extinguishment of debt	(4,539)	0	0
Gain on previously held equity interest	(4,853)	0	0
Gain on sale or acquisition, net	(3,017)	0	0
Deferred Income Tax Expense (Benefit)	(14,787)	0	0
Non-cash impairment charges	0	3,074	2,531
Loss (income) from discontinued operations	(4,589)	20,242	14,822
Costs associated with loan refinancing or payoff, net	6,166	627	1,877
Equity in income from joint ventures	(1,398)	(1,025)	(2,847)
Distributions from joint ventures	985	1,046	2,848
Depreciation and amortization	53,946	46,698	42,975
Amortization of deferred financing costs	4,041	4,218	3,807
Amortization of above and below Market Leases	48	0	0
Share-based compensation expense to management and trustees	6,516	5,833	5,610
Decrease (increase) in restricted cash	12,509	(6,681)	(652)
Increase in mortgage notes accrued interest receivable	(457)	(409)	(5)
Decrease (increase) in accounts receivable, net	(7,163)	(7,400)	129
Increase in direct financing lease receivable	(4,860)	(4,964)	(5,073)
Decrease (increase) in other assets	2,338	(989)	(44)
Increase in accounts payable and accrued liabilities	7,816	8,720	4,358
Increase in unearned rents	2,511	5,447	66
Net operating cash provided by continuing operations	231,439	196,101	185,668
Net operating cash provided by discontinued operations	2,681	11,343	10,248
Net cash provided by operating activities	234,120	207,444	195,916
Investing activities:
Acquisition of rental properties and other assets	(123,497)	(73,188)	(53,175)
Proceeds from sale of real estate	797	0	0
Investment in unconsolidated joint ventures	(1,607)	(1,800)	(3,970)
Investment in mortgage notes receivable	(60,568)	(113,823)	(19,688)
Proceeds from mortgage note receivable paydown	1,900	0	0
Investment in promissory notes receivable	(1,278)	0	0
Proceeds from promissory note receivable paydown	1,027	0	0
Investment in direct financing leases, net	(3,262)	0	(2,113)
Proceeds from Sale of Lease Receivables	0	4,494	0
Additions to properties under development	(197,271)	(113,599)	(57,926)
Net cash used by investing activities of continuing operations	(383,759)	(297,916)	(136,872)
Net cash used by other investing activities of discontinued operations	0	0	(58)
Net proceeds from sale of real estate from discontinued operations	47,301	42,133	226,612
Net cash provided (used) by investing activities	(336,458)	(255,783)	89,682
Financing activities:
Proceeds from long-term debt facilities	646,000	871,000	387,000
Principal payments on long-term debt	(552,468)	(658,571)	(425,859)
Deferred financing fees paid	(8,133)	(5,800)	(3,731)
Costs associated with loan refinancing or payoff (cash portion)	(5,790)	(189)	(117)
Net proceeds from issuance of common shares	220,785	231	253
Net proceeds from issuance of preferred shares	0	120,567	0
Redemption of preferred shares	0	(115,013)	(80,030)
Impact of stock option exercises, net	947	(1,987)	966
Purchase of common shares for treasury	(3,246)	(3,232)	(3,070)
Dividends paid to shareholders	(197,924)	(162,775)	(157,844)
Net cash provided (used) by financing activities	100,171	44,231	(282,432)
Effect of exchange rate changes on cash	(539)	147	(317)
Net increase (decrease) in cash and cash equivalents	(2,706)	(3,961)	2,849
Cash and cash equivalents at beginning of the year	10,664	14,625	11,776
Cash and cash equivalents at end of the year	7,958	10,664	14,625
Supplemental schedule of non-cash activity:
Transfer of property under development to rental property	139,026	96,178	41,087
Acquisition of real estate in exchange for assumption of debt at fair value	19,710	0	4,109
Issuance of nonvested shares and restricted share units at fair value, including nonvested shares issued for payment of bonuses	10,398	7,181	6,785
Conversion of equity to mortgage note receivable related to Atlantic-EPR I	0	14,852	0
Adjustment of noncontrolling interest to additional paid in capital	0	27,785	0
Sale of real estate in exchange for note receivable	2,500	2,500	0
Net increase in real estate and other assets	49,391	0	0
decrease in investment in joint venture	8,282	0	0
Decrease in mortgage notes receivable	33,089	0	0
Supplemental disclosure of cash flow information:
Cash paid during the year for interest	73,403	66,302	69,368
Cash paid (received) during the year for income taxes	$ 102	$ (325)	$ 40