Leases - Narrative (Details) ft² in Thousands, $ in Thousands	Mar. 31, 2019 USD ($) ft²	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Leases [Line Items]
Operating lease, right-of-use asset	$ 457,662		$ 0
Operating lease liabilities	484,173		0
Decrease in other liabilities	(292,187)		(311,806)
Decrease in deferred revenue	(71,328)		(167,730)
Decrease in identified intangible assets, net	(34,161)		(136,781)
Decrease in other assets	$ (497,219)		$ (431,938)
Accounting Standards Update 2016-02
Leases [Line Items]
Operating lease, right-of-use asset		$ 526,866
Operating lease liabilities		526,866
Decrease in other liabilities		37,269
Decrease in deferred revenue		4,267
Decrease in identified intangible assets, net		23,665
Decrease in other assets		$ 1,584
Farley Office and Retail Building
Leases [Line Items]
Equity method ownership percentage	95.00%
Square footage of real estate property (in sqft) | ft²	850
Lessee, operating lease, lease not yet commenced, term (years)	99 years
Farley Office and Retail Building | Office
Leases [Line Items]
Square footage of real estate property (in sqft) | ft²	730
Farley Office and Retail Building | Retail
Leases [Line Items]
Square footage of real estate property (in sqft) | ft²	120