Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Rental revenue	$ 122,391	$ 115,634	$ 360,348	$ 343,155
Tenant expense reimbursement	20,346	19,176	53,889	56,350
Observatory revenue	39,306	38,093	94,212	91,112
Third-party management and other fees	345	404	1,088	1,372
Other revenue and fees	4,932	2,541	19,861	6,748
Total revenues	187,320	175,848	529,398	498,737
Operating expenses:
Property operating expenses	41,270	38,585	122,009	115,075
Ground rent expenses	2,331	2,331	6,994	6,994
General and administrative expenses	12,899	11,798	36,566	35,623
Observatory expenses	8,648	7,250	23,079	21,900
Real estate taxes	26,901	24,691	76,001	71,773
Acquisition expenses	0	0	0	98
Depreciation and amortization	38,490	37,607	119,868	115,382
Total operating expenses	130,539	122,262	384,517	366,845
Total operating income	56,781	53,586	144,881	131,892
Other expenses:
Interest expense	(16,890)	(17,939)	(52,109)	(52,758)
Loss on early extinguishment of debt	(2,157)	0	(2,157)	(552)
Loss from derivative financial instruments	0	0	(289)	0
Income before income taxes	37,734	35,647	90,326	78,582
Income tax expense	(2,245)	(2,750)	(4,333)	(4,340)
Net income	35,489	32,897	85,993	74,242
Private perpetual preferred unit distributions	(234)	(234)	(702)	(702)
Net income attributable to non-controlling interests	(16,449)	(16,690)	(39,916)	(39,050)
Net income attributable to common stockholders	$ 18,806	$ 15,973	$ 45,375	$ 34,490
Total weighted average shares:
Basic (in shares)	158,102	136,831	157,796	126,740
Diluted (in shares)	297,871	280,614	298,089	271,028
Earnings per share attributable to common stockholders:
Basic (in USD per share)	$ 0.12	$ 0.12	$ 0.29	$ 0.27
Diluted (in USD per share)	0.12	0.12	0.29	0.27
Dividends per share (in USD per share)	$ 0.105	$ 0.105	$ 0.315	$ 0.295