Segment Reporting - Segment Revenue and Profit or Loss Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Rental revenue													$ 563,071	$ 586,414
Rental revenue															$ 493,231
Intercompany rental revenue													0	0	0
Tenant expense reimbursement													0	0	72,372
Observatory revenue													29,057	128,769	131,227
Lease termination fees													9,416	4,352	20,847
Third-party management and other fees													1,225	1,254	1,440
Other revenue and fees													6,459	10,554	12,394
Total revenues	$ 151,399	$ 146,575	$ 141,030	$ 170,224	$ 194,933	$ 192,873	$ 176,244	$ 167,293	$ 199,309	$ 186,402	$ 178,529	$ 167,271	609,228	731,343	731,511
Operating expenses:
Property operating expenses													136,141	174,977	167,379
Intercompany rent expense													0	0	0
Ground rent expenses													9,326	9,326	9,326
General and administrative expenses													62,244	61,063	52,674
Observatory expenses													23,723	33,767	32,767
Real estate taxes													121,923	115,916	110,000
Impairment charges													6,204	0	0
Depreciation and amortization													191,006	181,588	168,508
Total operating expenses													550,567	576,637	540,654
Total operating income	19,426	11,928	334	26,973	47,112	45,279	36,239	26,076	58,490	48,538	49,665	34,164	58,661	154,706	190,857
Other income (expense):
Interest income													2,637	11,259	10,661
Interest expense													(89,907)	(79,246)	(79,623)
Loss on early extinguishment of debt													(86)	0	0
IPO litigation expense													(1,165)	0	0
Income (loss) before income taxes													(29,860)	86,719	121,895
Income tax benefit (expense)													6,971	(2,429)	(4,642)
Net income (loss)	710	(12,269)	(19,618)	$ 8,288	28,720	$ 26,784	$ 18,930	$ 9,856	39,781	$ 29,230	$ 30,184	$ 18,058	(22,889)	84,290	117,253
Segment assets	4,150,695				3,931,834				4,195,780				4,150,695	3,931,834	4,195,780
Expenditures for segment assets													104,060	255,924	256,496
Intersegment Elimination
Revenues:
Intercompany rental revenue													(17,827)	(82,469)	(79,954)
Total revenues													(17,827)	(82,469)	(79,954)
Operating expenses:
Intercompany rent expense													(17,827)	(82,469)	(79,954)
General and administrative expenses													0	0	0
Impairment charges													0
Depreciation and amortization													0	0	0
Total operating expenses													(17,827)	(82,469)	(79,954)
Total operating income													0	0	0
Other income (expense):
Interest income													0	0	0
Interest expense													0	0	0
Loss on early extinguishment of debt													0
IPO litigation expense													0
Income (loss) before income taxes													0	0	0
Income tax benefit (expense)													0	0	0
Net income (loss)													0	0	0
Segment assets	0				0				0				0	0	0
Expenditures for segment assets													0	0	0
Real Estate
Operating expenses:
Impairment charges		$ 2,100	$ 4,100										6,200
Real Estate | Operating Segments
Revenues:
Rental revenue													563,071	586,414
Rental revenue															493,231
Intercompany rental revenue													17,827	82,469	79,954
Tenant expense reimbursement															72,372
Lease termination fees													9,416	4,352	20,847
Third-party management and other fees													1,225	1,254	1,440
Other revenue and fees													6,459	10,554	12,394
Total revenues													597,998	685,043	680,238
Operating expenses:
Property operating expenses													136,141	174,977	167,379
Intercompany rent expense													0	0	0
Ground rent expenses													9,326	9,326	9,326
General and administrative expenses													62,244	61,063	52,674
Real estate taxes													121,923	115,916	110,000
Impairment charges													6,204
Depreciation and amortization													190,863	181,558	168,430
Total operating expenses													526,701	542,840	507,809
Total operating income													71,297	142,203	172,429
Other income (expense):
Interest income													2,542	11,259	10,661
Interest expense													(89,907)	(79,246)	(79,623)
Loss on early extinguishment of debt													(86)
IPO litigation expense													(1,165)
Income (loss) before income taxes													(17,319)	74,216	103,467
Income tax benefit (expense)													(843)	(896)	(1,114)
Net income (loss)													(18,162)	73,320	102,353
Segment assets	3,903,884				3,671,211				3,930,330				3,903,884	3,671,211	3,930,330
Expenditures for segment assets													101,306	191,630	201,685
Observatory | Operating Segments
Revenues:
Intercompany rental revenue													0	0	0
Observatory revenue													29,057	128,769	131,227
Total revenues													29,057	128,769	131,227
Operating expenses:
Intercompany rent expense													17,827	82,469	79,954
General and administrative expenses													0	0	0
Observatory expenses													23,723	33,767	32,767
Impairment charges													0
Depreciation and amortization													143	30	78
Total operating expenses													41,693	116,266	112,799
Total operating income													(12,636)	12,503	18,428
Other income (expense):
Interest income													95	0	0
Interest expense													0	0	0
Loss on early extinguishment of debt													0
IPO litigation expense													0
Income (loss) before income taxes													(12,541)	12,503	18,428
Income tax benefit (expense)													7,814	(1,533)	(3,528)
Net income (loss)													(4,727)	10,970	14,900
Segment assets	$ 246,811				$ 260,623				$ 265,450				246,811	260,623	265,450
Expenditures for segment assets													$ 2,754	$ 64,294	$ 54,811