Consolidated Statements Of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
REVENUE
Rental Income	$ 841,461	$ 786,583	$ 727,812
Other property income	12,825	11,015	11,810
Mortgage interest income	3,062	3,993	4,390
Total revenue	857,348	801,591	744,012
EXPENSES
Rental expenses	164,890	158,326	147,593
Real estate taxes	107,839	95,286	85,824
General and administrative	36,281	33,399	35,645
Depreciation and amortization	216,050	193,585	174,796
Total operating expenses	525,060	480,596	443,858
OPERATING INCOME	332,288	320,995	300,154
Other interest income	475	374	149
Interest expense	(100,125)	(94,994)	(92,553)
Early extinguishment of debt	(12,273)	0	(19,072)
(Loss) income from real estate partnerships	(417)	50	1,416
INCOME FROM CONTINUING OPERATIONS	219,948	226,425	190,094
Gain on sale of real estate and change in control of interests, net	77,922	32,458	28,330
Net income	297,870	258,883	218,424
Net income attributable to noncontrolling interests	(7,956)	(8,973)	(8,205)
NET INCOME ATTRIBUTABLE TO THE TRUST	289,914	249,910	210,219
Dividends on preferred shares	(2,458)	(541)	(541)
NET INCOME AVAILABLE FOR COMMON SHAREHOLDERS	$ 287,456	$ 249,369	$ 209,678
EARNINGS PER COMMON SHARE, BASIC
Net income available for common shareholders	$ 3.97	$ 3.51	$ 3.04
Weighted average common shares outstanding, basic	72,117	70,877	68,797
EARNINGS PER COMMON SHARE, DILUTED
Net income available for common shareholders	$ 3.97	$ 3.50	$ 3.03
Weighted average number of common shares, diluted	72,233	71,049	68,981
Comprehensive Income
Net income	$ 297,870	$ 258,883	$ 218,424
Other comprehensive income (loss) - change in value of interest rate swaps	2,599	1,533	(595)
COMPREHENSIVE INCOME	300,469	260,416	217,829
Comprehensive income attributable to noncontrolling interests	(7,956)	(8,973)	(8,205)
COMPREHENSIVE INCOME ATTRIBUTABLE TO THE TRUST	$ 292,513	$ 251,443	$ 209,624