Property, Plant and Equipment and Leasehold Intangibles, Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment and leasehold intangibles gross	$ 8,825,201		$ 8,825,201		$ 8,916,465
Accumulated depreciation and amortization	(3,109,270)		(3,109,270)		(3,064,320)
Property, plant and equipment and leasehold intangibles, net	5,715,931		5,715,931		5,852,145
Depreciation and amortization expense	115,300	$ 117,900	228,700	$ 244,500
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment and leasehold intangibles gross	473,580		473,580		449,295
Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment and leasehold intangibles gross	5,057,848		5,057,848		4,923,621
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment and leasehold intangibles gross	121,542		121,542		124,850
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment and leasehold intangibles gross	1,040,220		1,040,220		1,006,889
Resident and Leasehold Operating Intangibles [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment and leasehold intangibles gross	550,876		550,876		594,748
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment and leasehold intangibles gross	50,245		50,245		74,678
Assets Under Capital and Financing Leases [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment and leasehold intangibles gross	$ 1,530,890		$ 1,530,890		$ 1,742,384