Consolidated Statements of Capital - USD ($) $ in Thousands	3 Months Ended						12 Months Ended
	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance		$ 1,982,863		$ 1,372,686		$ 1,381,097	$ 1,982,863	$ 1,372,686	$ 1,381,097
Issuance of OP units, net of costs								611,206
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital							0	0	0
Equity compensation							14,100	9,729	5,483
Distributions							(126,963)	(114,954)	(91,900)
Net income	$ 32,260	$ 19,145	$ 33,008	$ 16,705	$ 19,370	$ 7,888	118,253	107,250	79,928
Unrealized loss on valuation of interest rate swap agreements							(11,658)	(3,054)	(1,922)
Other comprehensive income (loss)							(10,516)	(3,054)	(1,922)
Ending balance	$ 1,977,737		$ 1,982,863		$ 1,372,686		$ 1,977,737	$ 1,982,863	$ 1,372,686
General Partner [Member] | Series PR Operating Partnership Units [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		155,841,000		120,023,000		107,191,000	155,841,000	120,023,000	107,191,000
Beginning balance		$ 1,154,136		$ 524,729		$ 468,638	$ 1,154,136	$ 524,729	$ 468,638
Issuance of OP units, net (in units)								29,611,000
Issuance of OP units, net of costs								$ 611,206
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital (in units)							5,615,000	6,167,000	12,818,000
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital							$ 23,435	$ 23,678	$ 62,070
Equity compensation (in units)							21,000	40,000	14,000
Equity compensation							$ 468	$ 357	$ 296
Distributions							(66,789)	(55,812)	(39,183)
Net income							62,647	51,456	33,730
Unrealized loss on valuation of interest rate swap agreements								$ (1,478)	$ (822)
Other comprehensive income (loss)							$ (5,615)
Ending balance (in units)	161,477,000		155,841,000		120,023,000		161,477,000	155,841,000	120,023,000
Ending balance	$ 1,168,282		$ 1,154,136		$ 524,729		$ 1,168,282	$ 1,154,136	$ 524,729
Limited Partner [Member] | Series PR Operating Partnership Units [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		93,075,000		93,863,000		100,211,000	93,075,000	93,863,000	100,211,000
Beginning balance		$ 793,360		$ 809,901		$ 868,163	$ 793,360	$ 809,901	$ 868,163
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital (in units)							(2,611,000)	(2,657,000)	(6,803,000)
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital							$ (21,997)	$ (22,264)	$ (58,636)
Equity compensation (in units)							1,296,000	1,869,000	455,000
Equity compensation							$ 13,632	$ 9,372	$ 5,187
Distributions							(38,969)	(37,621)	(32,794)
Net income							35,430	34,977	28,678
Unrealized loss on valuation of interest rate swap agreements								$ (1,005)	$ (697)
Other comprehensive income (loss)							$ (3,177)
Ending balance (in units)	91,760,000		93,075,000		93,863,000		91,760,000	93,075,000	93,863,000
Ending balance	$ 778,279		$ 793,360		$ 809,901		$ 778,279	$ 793,360	$ 809,901
Limited Partner [Member] | Series ES Operating Partnership Units [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		35,728,000		38,262,000		42,365,000	35,728,000	38,262,000	42,365,000
Beginning balance		$ 20,091		$ 22,074		$ 26,488	$ 20,091	$ 22,074	$ 26,488
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital (in units)							(1,954,000)	(2,534,000)	(4,103,000)
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital							$ (978)	$ (1,075)	$ (2,424)
Distributions							(14,477)	(14,642)	(13,495)
Net income							13,726	14,140	11,792
Unrealized loss on valuation of interest rate swap agreements								$ (406)	$ (287)
Other comprehensive income (loss)							$ (1,230)
Ending balance (in units)	33,774,000		35,728,000		38,262,000		33,774,000	35,728,000	38,262,000
Ending balance	$ 17,132		$ 20,091		$ 22,074		$ 17,132	$ 20,091	$ 22,074
Limited Partner [Member] | Series 60 Operating Partnership Units [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		9,701,000		10,318,000		11,546,000	9,701,000	10,318,000	11,546,000
Beginning balance		$ 4,880		$ 5,366		$ 6,567	$ 4,880	$ 5,366	$ 6,567
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital (in units)							(713,000)	(617,000)	(1,228,000)
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital							$ (310)	$ (218)	$ (654)
Distributions							(3,889)	(3,985)	(3,665)
Net income							3,637	3,827	3,196
Unrealized loss on valuation of interest rate swap agreements								$ (110)	$ (78)
Other comprehensive income (loss)							$ (326)
Ending balance (in units)	8,988,000		9,701,000		10,318,000		8,988,000	9,701,000	10,318,000
Ending balance	$ 3,992		$ 4,880		$ 5,366		$ 3,992	$ 4,880	$ 5,366
Limited Partner [Member] | Series 250 Operating Partnership Units [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		4,747,000		5,106,000		5,790,000	4,747,000	5,106,000	5,790,000
Beginning balance		$ 2,392		$ 2,612		$ 3,237	$ 2,392	$ 2,612	$ 3,237
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital (in units)							(337,000)	(359,000)	(684,000)
Conversion of operating partnership units to Class A shares and Class B shares to ESRT partner's capital							$ (150)	$ (121)	$ (356)
Distributions							(1,903)	(1,958)	(1,827)
Net income							1,877	1,914	1,596
Unrealized loss on valuation of interest rate swap agreements								$ (55)	$ (38)
Other comprehensive income (loss)							$ (168)
Ending balance (in units)	4,410,000		4,747,000		5,106,000		4,410,000	4,747,000	5,106,000
Ending balance	$ 2,048		$ 2,392		$ 2,612		$ 2,048	$ 2,392	$ 2,612
Private Perpetual Preferred Units [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		1,560,000		1,560,000		1,560,000	1,560,000	1,560,000	1,560,000
Beginning balance		$ 8,004		$ 8,004		$ 8,004	$ 8,004	$ 8,004	$ 8,004
Distributions							(936)	(936)	(936)
Net income							$ 936	$ 936	$ 936
Ending balance (in units)	1,560,000		1,560,000		1,560,000		1,560,000	1,560,000	1,560,000
Ending balance	$ 8,004		$ 8,004		$ 8,004		$ 8,004	$ 8,004	$ 8,004