Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues:
Rental revenue	$ 112,613	$ 112,866	$ 227,521	$ 222,924
Tenant expense reimbursement	19,054	18,582	37,174	36,782
Observatory revenue	31,838	30,600	53,019	48,823
Construction revenue	0	374	0	1,981
Third-party management and other fees	423	594	968	1,040
Other revenue and fees	1,887	1,757	4,207	5,105
Total revenues	165,815	164,773	322,889	316,655
Operating expenses:
Property operating expenses	37,386	37,262	76,490	79,289
Ground rent expenses	2,330	2,332	4,663	4,663
General and administrative expenses	12,907	9,113	23,825	18,213
Observatory expenses	6,895	8,093	14,650	15,495
Construction expenses	0	353	0	3,222
Real estate taxes	23,557	22,952	47,082	45,930
Acquisition expenses	0	0	98	0
Depreciation and amortization	38,548	39,629	77,775	81,047
Total operating expenses	121,623	119,734	244,583	247,859
Total operating income (loss)	44,192	45,039	78,306	68,796
Interest expense	(17,420)	(17,571)	(35,371)	(33,618)
Income before income taxes	26,772	27,468	42,935	35,178
Income tax expense	(2,132)	(883)	(1,590)	(705)
Net income (loss)	24,640	26,585	41,345	34,473
Private perpetual preferred unit distributions	(234)	(234)	(468)	(468)
Net income attributable to non-controlling interests	(13,317)	(15,231)	(22,360)	(19,747)
Net income attributable to common stockholders	$ 11,089	$ 11,120	$ 18,517	$ 14,258
Total weighted average shares:
Basic (in shares)	122,502	112,852	121,640	111,136
Diluted (in shares)	266,167	265,867	267,121	265,866
Earnings per share attributable to common stockholders:
Basic (in USD per share)	$ 0.09	$ 0.10	$ 0.15	$ 0.13
Diluted (in USD per share)	0.09	0.10	0.15	0.13
Dividends per share (in USD per share)	$ 0.105	$ 0.085	$ 0.19	$ 0.17