Segment Reporting Segment Revenue and Profit or Loss Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended											9 Months Ended	12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Oct. 06, 2013	Dec. 31, 2014	Dec. 31, 2012
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue						$ 79,987						$ 148,690	$ 400,825	$ 196,187
Intercompany rental revenue													0	0
Tenant expense reimbursement						15,836						21,272	67,651	29,483
Observatory revenue						23,735							111,541
Construction revenue						5,265						18,636	38,648	18,902
Third-party management and other fees						550						5,067	2,376	5,103
Other revenue and fees						2,210						12,407	14,285	10,619
Total revenues	170,411	[1]	169,441	155,168	140,306	127,583	149,388	[1]	62,278	59,569	62,420	206,072	635,326	260,294
Property operating expenses						34,055						41,297	151,048	55,707
Intercompany rent expense													0
Ground rent expenses						398							5,339
Marketing, general, and administrative expenses						16,379						23,600	39,037	20,963
Observatory expenses						5,687							29,041
Construction expenses						5,468						19,821	38,596	19,592
Real estate taxes						17,191						24,331	82,131	30,406
Acquisition expenses						138,140							3,382
Depreciation and amortization						27,375						38,963	145,431	42,690
Total operating expenses						244,693						152,519	494,005	171,605
Total operating income (loss)	31,282		43,412	42,539	24,088	(117,110)						53,553	141,321	88,689
Interest expense						(13,147)						(50,660)	(66,456)	(54,394)
Gain on consolidation of non-controlled entities						322,563							0
Income (loss) before income taxes						192,306						(37,232)	74,865	48,643
Income tax (expense) benefit						1,125							(4,655)
Net income (loss)	10,964		22,734	25,281	11,231	193,431	148,917	[1]	2,281	3,071	1,930	(37,232)	70,210	48,643
Investment in non-controlled entities												88,304		76,879
Segment assets	3,296,495					2,476,061	2,476,061					1,033,918	3,296,495	975,674
Expenditures for segment assets						56,434						55,950	497,744	87,659
Formation transaction expenses						0						4,507	0	2,247
Equity in net income of non-controlled entities						0						14,875	0	14,348
Deemed contribution for settlement expense						0						(55,000)	0
Intersegment Eliminations [Member]
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue						0						0	0	0
Intercompany rental revenue						(20,134)						(56)	(69,293)	(74)
Tenant expense reimbursement						0						0	0	0
Observatory revenue						0							0
Construction revenue						(1,536)						(6,837)	(6,341)	(5,714)
Third-party management and other fees						0						0	0	0
Other revenue and fees						(1)						0	0	0
Total revenues						(21,671)						(6,893)	(75,634)	(5,788)
Property operating expenses						0						0	0	265
Intercompany rent expense						(20,134)							(69,293)
Ground rent expenses						0							0
Marketing, general, and administrative expenses						4						0	0	0
Observatory expenses						0							0
Construction expenses						(1,324)						(6,003)	(5,589)	(5,142)
Real estate taxes						0						0	0	0
Acquisition expenses						0							0
Depreciation and amortization						(10)						(19)	0	0
Total operating expenses						(21,464)						(6,022)	(74,882)	(4,877)
Total operating income (loss)						(207)						(871)	(752)	(911)
Interest expense						0						0	0	0
Gain on consolidation of non-controlled entities						0
Income (loss) before income taxes						(207)						(871)	(752)	(911)
Income tax (expense) benefit						0							0
Net income (loss)						(207)							(752)
Investment in non-controlled entities												0		0
Segment assets	0					0	0					0	0	0
Expenditures for segment assets						0						0		0
Formation transaction expenses												0		0
Equity in net income of non-controlled entities												0		0
Deemed contribution for settlement expense												0
Real Estate [Member] | Operating Segments [Member]
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue						79,987						148,690	400,825	196,187
Intercompany rental revenue						20,134						56	69,293	74
Tenant expense reimbursement						15,836						21,272	67,651	29,483
Observatory revenue						0							0
Construction revenue						0						0	0	0
Third-party management and other fees						550						5,067	2,376	5,103
Other revenue and fees						2,211						12,407	13,280	10,619
Total revenues						118,718						187,492	553,425	241,466
Property operating expenses						34,055						41,297	151,048	55,442
Intercompany rent expense						0							0
Ground rent expenses						398							5,339
Marketing, general, and administrative expenses						16,375						23,600	39,037	20,963
Observatory expenses						0							0
Construction expenses						0						0	0	0
Real estate taxes						17,191						24,331	82,131	30,406
Acquisition expenses						138,140							3,382
Depreciation and amortization						27,376						38,963	145,121	42,661
Total operating expenses						233,535						132,698	426,058	151,719
Total operating income (loss)						(114,817)						54,794	127,367	89,747
Interest expense						(13,147)						(50,660)	(66,456)	(54,394)
Gain on consolidation of non-controlled entities						322,563
Income (loss) before income taxes						194,599						(35,991)	60,911	49,701
Income tax (expense) benefit						0							(1,437)
Net income (loss)						194,599							59,474
Investment in non-controlled entities												88,304		76,879
Segment assets	3,036,087					2,218,143	2,218,143					1,023,333	3,036,087	964,160
Expenditures for segment assets						56,434						55,820	497,645	87,659
Formation transaction expenses												4,507		2,247
Equity in net income of non-controlled entities												14,875		14,348
Deemed contribution for settlement expense												(55,000)
Observatory [Member] | Operating Segments [Member]
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue						0							0
Intercompany rental revenue						0							0
Tenant expense reimbursement						0							0
Observatory revenue						23,735							111,541
Construction revenue						0							0
Third-party management and other fees						0							0
Other revenue and fees						0							982
Total revenues						23,735							112,523
Property operating expenses						0							0
Intercompany rent expense						20,134							69,293
Ground rent expenses						0							0
Marketing, general, and administrative expenses						0							0
Observatory expenses						5,687							29,041
Construction expenses						0							0
Real estate taxes						0							0
Acquisition expenses						0							0
Depreciation and amortization						4							295
Total operating expenses						25,825							98,629
Total operating income (loss)						(2,090)							13,894
Interest expense						0							0
Gain on consolidation of non-controlled entities						0
Income (loss) before income taxes						(2,090)							13,894
Income tax (expense) benefit						1,125							(2,876)
Net income (loss)						(965)							11,018
Segment assets	252,376					249,084	249,084						252,376
Expenditures for segment assets						0							99
Other [Member] | Operating Segments [Member]
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue						0						0	0	0
Intercompany rental revenue						0						0	0	0
Tenant expense reimbursement						0						0	0	0
Observatory revenue						0							0
Construction revenue						6,801						25,473	44,989	24,616
Third-party management and other fees						0						0	0	0
Other revenue and fees						0						0	23	0
Total revenues						6,801						25,473	45,012	24,616
Property operating expenses						0						0	0	0
Intercompany rent expense						0							0
Ground rent expenses						0							0
Marketing, general, and administrative expenses						0						0	0	0
Observatory expenses						0							0
Construction expenses						6,792						25,824	44,185	24,734
Real estate taxes						0						0	0	0
Acquisition expenses						0							0
Depreciation and amortization						5						19	15	29
Total operating expenses						6,797						25,843	44,200	24,763
Total operating income (loss)						4						(370)	812	(147)
Interest expense						0						0	0	0
Gain on consolidation of non-controlled entities						0
Income (loss) before income taxes						4						(370)	812	(147)
Income tax (expense) benefit						0							(342)
Net income (loss)						4							470
Investment in non-controlled entities												0		0
Segment assets	8,032					8,834	8,834					10,585	8,032	11,514
Expenditures for segment assets						0						130	0	0
Formation transaction expenses												0		0
Equity in net income of non-controlled entities												0		0
Deemed contribution for settlement expense												$ 0

[1] The results of operations of our predecessor for October 1, 2013 through October 6, 2013 and the results of operations of our company for October 7, 2013 through December 31, 2013 have been combined.