Revenue Recognition (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Number of reportable segments | segment									2
Cumulative effect of accounting change	$ 14,519								$ 14,519
Base rent									1,623,122	$ 1,583,443	$ 1,538,605
Property rentals									1,760,205	1,714,952	1,662,093
Operating expense reimbursements									193,207	179,381	166,103
Tenant services									53,921	54,043	55,460
Tenant expense reimbursements									247,128	233,424	221,563
BMS cleaning fees									120,357	104,143	93,425
Management and leasing fees									13,324	10,087	8,243
Lease termination fees									2,144	8,171	8,770
Other income									20,562	13,349	9,648
Fee and other income									156,387	135,750	120,086
Total revenues	$ 543,417	$ 542,048	$ 541,818	$ 536,437	$ 536,226	$ 528,755	$ 511,087	$ 508,058	2,163,720	2,084,126	2,003,742
Hotel Pennsylvania
Disaggregation of Revenue [Line Items]
Property rentals									94,399	89,302	80,785
Trade Shows
Disaggregation of Revenue [Line Items]
Property rentals									42,684	42,207	42,703
New York
Disaggregation of Revenue [Line Items]
Base rent									1,371,182	1,347,270	1,313,611
Property rentals									1,465,581	1,436,572	1,394,396
Operating expense reimbursements									177,044	165,347	154,734
Tenant services									41,351	42,273	44,304
Tenant expense reimbursements									218,395	207,620	199,038
BMS cleaning fees									129,088	110,986	97,612
Management and leasing fees									12,203	8,599	7,531
Lease termination fees									858	7,955	7,705
Other income									9,911	7,575	7,092
Fee and other income									152,060	135,115	119,940
Total revenues									1,836,036	1,779,307	1,713,374
New York | Hotel Pennsylvania
Disaggregation of Revenue [Line Items]
Property rentals									94,399	89,302	80,785
New York | Trade Shows
Disaggregation of Revenue [Line Items]
Property rentals									0	0	0
Other
Disaggregation of Revenue [Line Items]
Base rent									251,940	236,173	224,994
Property rentals									294,624	278,380	267,697
Operating expense reimbursements									16,163	14,034	11,369
Tenant services									12,570	11,770	11,156
Tenant expense reimbursements									28,733	25,804	22,525
BMS cleaning fees									(8,731)	(6,843)	(4,187)
Management and leasing fees									1,121	1,488	712
Lease termination fees									1,286	216	1,065
Other income									10,651	5,774	2,556
Fee and other income									4,327	635	146
Total revenues									327,684	304,819	290,368
Other | Hotel Pennsylvania
Disaggregation of Revenue [Line Items]
Property rentals									0	0	0
Other | Trade Shows
Disaggregation of Revenue [Line Items]
Property rentals									$ 42,684	$ 42,207	$ 42,703
Earnings Less Than Distributions | Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Cumulative effect of accounting change												$ 14,519