Segment Reporting Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 segment		Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of reportable segments	2
Total revenues	$ 140,306		$ 62,420
Interest expense	(14,337)
Depreciation and amortization expense	(30,115)
Equity in net income of non-controlled entities	0		1,819
Segment profit (loss)	4,369
Segment assets	2,450,416			2,476,061
Investment in non-controlled entities			77,567		76,879
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	(16,230)		(2,791)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	156,536		65,148
Total [Member]
Segment Reporting Information [Line Items]
Total revenues	140,306		62,357
All operating expenses, excluding noncash items	(100,723)		(30,363)
Interest expense	(14,337)		(14,196)
Depreciation and amortization expense	(30,115)		(12,156)
Equity in net income of non-controlled entities			1,819
Segment assets	2,450,416		1,008,340
Investment in non-controlled entities			77,567
Expenditures for segment assets	17,243		13,043
Total [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	16,230		2,791
Total [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	156,536		65,148
Segment profit (loss)	11,361		10,252
Real Estate [Member]
Segment Reporting Information [Line Items]
Total revenues	108,027		56,175
All operating expenses, excluding noncash items	(65,562)		(21,604)
Interest expense	(14,337)		(14,196)
Depreciation and amortization expense	(30,051)		(12,149)
Equity in net income of non-controlled entities			1,819
Segment assets	2,191,390		997,316
Investment in non-controlled entities			77,567
Expenditures for segment assets	17,243		13,043
Real Estate [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	15,268	[1]	18
Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	123,295		56,193
Segment profit (loss)	13,345		10,063
Observatory [Member]
Segment Reporting Information [Line Items]
Total revenues	17,301
All operating expenses, excluding noncash items	(20,046)
Interest expense	0
Depreciation and amortization expense	(61)
Segment assets	245,999
Expenditures for segment assets	0
Observatory [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	0
Observatory [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	17,301
Segment profit (loss)	(2,806)
Other [Member]
Segment Reporting Information [Line Items]
Total revenues	14,978		6,182
All operating expenses, excluding noncash items	(15,115)		(8,759)
Interest expense	0		0
Depreciation and amortization expense	(3)		(7)
Equity in net income of non-controlled entities			0
Segment assets	13,027		11,024
Investment in non-controlled entities			0
Expenditures for segment assets	0		0
Other [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	962		2,773
Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	15,940		8,955
Segment profit (loss)	$ 822		$ 189

[1] The observatory pays a market-based rent payment comprised of fixed and percentage rent to the Empire State Building.