Consolidated Statement of Changes in Partner Capital Statement - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income	$ 13,310	$ 57,944	$ 8,101	$ 202,127
Other comprehensive loss
Amounts reclassified from accumulated other comprehensive loss	2,570	1,677	6,479	2,085
Contributions from partners	312	103	443	1,999
Issuance of exchangeable operating partnership units		25,869	1,275	25,869
Exchangeable operating partnership units issued for acquisition of real estate		25,869	1,275	25,869
Distributions to partners	(2,211)	(1,358)	(4,029)	(4,222)
Restricted units issued as a result of restricted stock issued by Parent Company, net of amortization	3,372	4,224	10,964	12,127
Deferred compensation plan, net	207		207
Partners Capital Total [Member]
Net income	12,688	56,965	6,402	199,139
Other comprehensive loss
Amounts reclassified from accumulated other comprehensive loss	2,466	1,688	6,282	2,143
Reallocation of limited partner's interest				66
Restricted units issued as a result of restricted stock issued by Parent Company, net of amortization	3,372	4,224	10,964	12,127
Deferred compensation plan, net	207		207
Partnership Interest [Member]
Beginning Balance	6,197,202	6,352,848	6,289,961	6,450,168
Net income	13,310	57,944	8,101	202,127
Other comprehensive loss
Other comprehensive loss before reclassification	(613)	(3,682)	(18,808)	(18,138)
Amounts reclassified from accumulated other comprehensive loss	2,570	1,677	6,479	2,085
Contributions from partners	312	103	443	1,999
Issuance of exchangeable operating partnership units		25,869	1,275	25,869
Exchangeable operating partnership units issued for acquisition of real estate		25,869	1,275	25,869
Distributions to partners	(103,615)	(99,581)	(307,073)	(298,841)
Restricted units issued as a result of restricted stock issued by Parent Company, net of amortization	3,372	4,224	10,964	12,128
Common units repurchased and retired as a result of common stock repurchased and retired by Parent Company				(32,778)
Common units issued as a result of common stock issued by Parent Company, net of issuance costs		445	125,608
Ending Balance	6,113,123	6,339,847	6,113,123	6,339,847
Deferred compensation plan, net	207		207
Common units redeemed as a result of common stock redeemed by Parent Company, net of issuances			(4,034)	(4,772)
Partnership Interest [Member] | Partners Capital Total [Member]
Beginning Balance	6,158,359	6,311,369	6,249,448	6,408,636
Net income	12,745	57,122	6,431	199,595
Other comprehensive loss
Other comprehensive loss before reclassification	(553)	(3,419)	(17,584)	(17,062)
Amounts reclassified from accumulated other comprehensive loss	2,477	1,693	6,310	2,149
Issuance of exchangeable operating partnership units		25,869	1,275	25,869
Exchangeable operating partnership units issued for acquisition of real estate		25,869	1,275	25,869
Distributions to partners	(101,404)	(98,223)	(303,044)	(294,619)
Reallocation of limited partner's interest				(66)
Restricted units issued as a result of restricted stock issued by Parent Company, net of amortization	3,372	4,224	10,964	12,128
Common units repurchased and retired as a result of common stock repurchased and retired by Parent Company				(32,778)
Common units issued as a result of common stock issued by Parent Company, net of issuance costs		445	125,608
Ending Balance	6,075,581	6,299,080	6,075,581	6,299,080
Deferred compensation plan, net	207		207
Common units redeemed as a result of common stock redeemed by Parent Company, net of issuances			(4,034)	(4,772)
Partnership Interest [Member] | AOCI Attributable to Parent [Member]
Beginning Balance	(25,135)	(14,086)	(11,997)	(927)
Other comprehensive loss
Other comprehensive loss before reclassification	(551)	(3,406)	(17,505)	(17,020)
Amounts reclassified from accumulated other comprehensive loss	2,466	1,688	6,282	2,143
Ending Balance	(23,220)	(15,804)	(23,220)	(15,804)
Partnership Interest [Member] | Noncontrolling Interest [Member]
Beginning Balance	38,843	41,479	40,513	41,532
Net income	565	822	1,670	2,532
Other comprehensive loss
Other comprehensive loss before reclassification	(60)	(263)	(1,224)	(1,076)
Amounts reclassified from accumulated other comprehensive loss	93	(16)	169	(64)
Contributions from partners	312	103	443	1,999
Distributions to partners	(2,211)	(1,358)	(4,029)	(4,222)
Reallocation of limited partner's interest				66
Ending Balance	37,542	40,767	37,542	40,767
Partnership Interest [Member] | General Partner [Member]
Beginning Balance	6,147,118	6,314,927	6,225,345	6,398,897
Net income	12,688	56,965	6,402	199,139
Other comprehensive loss
Distributions to partners	(100,949)	(98,018)	(301,678)	(294,005)
Reallocation of limited partner's interest				(66)
Restricted units issued as a result of restricted stock issued by Parent Company, net of amortization	3,372	4,224	10,964	12,128
Common units repurchased and retired as a result of common stock repurchased and retired by Parent Company				(32,778)
Common units issued as a result of common stock issued by Parent Company, net of issuance costs		445	125,608
Ending Balance	6,062,814	6,278,543	6,062,814	6,278,543
Deferred compensation plan, net	207		207
Common units redeemed as a result of common stock redeemed by Parent Company, net of issuances			(4,034)	(4,772)
Partnership Interest [Member] | Limited Partner [Member]
Beginning Balance	36,376	10,528	36,100	10,666
Net income	57	157	29	456
Other comprehensive loss
Other comprehensive loss before reclassification	(2)	(13)	(79)	(42)
Amounts reclassified from accumulated other comprehensive loss	11	5	28	6
Issuance of exchangeable operating partnership units		25,869	1,275	25,869
Exchangeable operating partnership units issued for acquisition of real estate		25,869	1,275	25,869
Distributions to partners	(455)	(205)	(1,366)	(614)
Ending Balance	$ 35,987	$ 36,341	$ 35,987	$ 36,341