Summary of Significant Accounting Policies - Balance Sheet Adoption Effect (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets, net	$ 185,017		$ 106,189
Property, plant and equipment and leasehold intangibles, net	5,236,194		5,275,427
Operating lease right-of-use assets	1,291,428		0
Investment in unconsolidated ventures	27,747		27,528
Other intangible assets, net	45,930		51,472
Other assets, net	81,531		160,418
Total assets	7,630,773		6,467,260
Refundable fees and deferred revenue	95,212		62,494
Total lease obligations	1,576,383
Deferred liabilities	6,007		262,761
Other liabilities	157,290		197,289
Total liabilities	6,713,176		5,448,847
Total equity	$ 917,597	$ 962,528	$ 1,018,413	$ 1,079,561	$ 1,530,291
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets, net		67,000
Property, plant and equipment and leasehold intangibles, net		(11,000)
Operating lease right-of-use assets		1,329,000
Investment in unconsolidated ventures		(2,000)
Other intangible assets, net		(5,000)
Other assets, net		(73,000)
Total assets		1,305,000
Refundable fees and deferred revenue		43,000
Total lease obligations		1,618,000
Deferred liabilities		(257,000)
Other liabilities		(43,000)
Total liabilities		1,361,000
Total equity		$ (56,000)