Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Net Income (Loss) Available to Common Stockholders, Diluted	$ 109,141	$ 99,328
Operating activities:
Net income	126,997	117,183
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Gain on early extinguishment of debt	0	(4,539)
Provision for loan loss	3,777	0
Income from discontinued operations	(3,384)	(3,931)
Gain on sale of land	(330)	0
gain on sale of investment in a direct financing lease	(220)	0
Costs associated with loan refinancing or payoff	0	6,166
Equity in income from joint ventures	878	1,168
Distributions from joint ventures	810	630
Depreciation and amortization	48,750	39,140
Amortization of deferred financing costs	3,158	2,997
Amortization of above and below Market Leases	144	0
Share-based compensation expense to management and trustees	6,984	4,825
Decrease (increase) in restricted cash	(1,490)	12,638
Increase in mortgage notes accrued interest receivable	(2,323)	(1,240)
Increase in accounts receivable, net	(2,585)	(4,542)
Increase in direct financing lease receivable	(2,211)	(3,638)
Decrease (increase) in other assets	(2,413)	1,400
Decrease in accounts payable and accrued liabilities	(8,095)	(9,327)
Increase (decrease) in unearned rents and interest	1,408	(441)
Net operating cash provided by continuing operations	168,099	156,153
Net operating cash provided by discontinued operations	109	2,222
Net cash provided by operating activities	168,208	158,375
Investing activities:
Acquisition of rental properties and other assets	56,385	27,199
Proceeds from sale of real estate	3,647	796
Investment in unconsolidated joint ventures	0	(1,021)
Proceeds from settlement of derivative	(5,725)	0
Investment in mortgage notes receivable	(57,922)	(56,864)
Proceeds from mortgage note receivable paydown	317	1,835
Investment in promissory notes receivable	4,387	1,278
Proceeds from promissory note receivable paydown	0	1,026
Investment in a direct financing lease, net	0	3,262
Proceeds from sale of investments in a direct financing lease, net	46,092	0
Additions to properties under development	(256,528)	(144,525)
Net cash used by investing activities of continuing operations	(319,441)	(230,492)
Net proceeds from sale of real estate from discontinued operations	0	46,490
Net cash used by investing activities	(319,441)	(184,002)
Financing activities:
Proceeds from long-term debt facilities	265,000	549,000
Principal payments on long-term debt	(220,566)	(384,831)
Deferred financing fees paid	(808)	(8,106)
Costs associated with loan refinancing or payoff (cash portion)	0	(5,790)
Net proceeds from issuance of common shares	264,008	43,659
Impact of stock option exercises, net	(27)	947
Purchase of common shares for treasury	(2,892)	(3,246)
Dividends paid to shareholders	(152,874)	(152,195)
Net cash provided by financing activities	151,841	39,438
Effect of exchange rate changes on cash	(180)	(334)
Net increase in cash and cash equivalents	428	13,477
Cash and cash equivalents at beginning of the year	7,958	10,664
Cash and cash equivalents at end of the year	8,386	24,141
Supplemental schedule of non-cash activity:
Transfer of property under development to rental property	152,504	83,685
Acquisition of real estate in exchange for assumption of debt at fair value	101,441	19,710
Issuance of nonvested shares and restricted share units at fair value, including nonvested shares issued for payment of bonuses	15,525	10,398
Supplemental disclosure of cash flow information:
Cash paid during the year for interest	76,836	66,494
Cash paid (received) during the period for income taxes	$ 234	$ (116)