Investments and Dispositions (Details)			3 Months Ended		9 Months Ended
	Apr. 06, 2017 USD ($) properties $ / shares shares	Mar. 30, 2017 USD ($)	Sep. 30, 2017 USD ($) properties	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment properties shares	Sep. 30, 2016 USD ($)
Real Estate Properties [Line Items]
Rental Properties	$ 481,006,000
Gain on sale of real estate			$ 997,000	$ 1,615,000	$ 28,462,000	$ 3,885,000
Number of leases assumed | properties	3
Number of properties subject to assumed ground leases | properties	9
Payments to Acquire Productive Assets					1,500,000,000
Stock Issued During Period, Value, Acquisitions	$ 657,500,000				657,473,000
Proceeds from mortgage note receivable paydown					$ 16,608,000	63,876,000
Number of Reportable Operating Segments | segment					4
Prepaymentfee						$ 3,600,000
Indefinite-Lived Trade Names	6,355,000
Below Market Lease, Net	$ (7,611,000)
Number of Properties Securing Mortgage Note | properties			9		9
Closing Price at Acquisition Date | $ / shares	$ 74.28
Payments to Acquire Property, Plant, and Equipment	$ 61,200,000
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	$ 12,100,000
Education Property Member
Real Estate Properties [Line Items]
number of properties sold pursuant to tenant purchase option					5
number of properties sold					2
attractions [Member]
Real Estate Properties [Line Items]
Number of properties acquired (in properties) | properties	15
Proceeds from Sale of Property, Plant, and Equipment	$ 2,500,000
number of properties sold	1
family entertainment center [Member]
Real Estate Properties [Line Items]
Number of properties acquired (in properties) | properties	5
Proceeds from Sale of Property, Plant, and Equipment	$ 6,800,000
number of properties sold	5
attractions and family entertainment centers [Member]
Real Estate Properties [Line Items]
Gain on sale of real estate	$ 0
Property, Plant and Equipment, Additions	$ 479,800,000
Ski Resorts [Member]
Real Estate Properties [Line Items]
mortgage loans on real estate term	5
number of extension options	3
Extension option term	2 years 6 months
Mortgage Loans on Real Estate, Interest Rate	8.50%
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ 3,000,000
Property, Plant and Equipment, Additions	374,500,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	$ 251,038,000
Number of Properties Securing Mortgage Note | properties	14
Entertainment Reportable Operating Segment [Member]
Real Estate Properties [Line Items]
Proceeds from Sale of Property, Plant, and Equipment					$ 72,300,000
Gain on sale of real estate					19,400,000
Payments to Acquire Productive Assets					$ 264,900,000
Proceeds from mortgage note receivable paydown		$ 4,000,000.0
number of properties sold					4
Prepaymentfee		$ 800,000
Entertainment Reportable Operating Segment [Member] | Theatre Properties [Member]
Real Estate Properties [Line Items]
Number of properties acquired (in properties)					6
Payments to Acquire Productive Assets					$ 154,100,000
Education Reportable Operating Segment [Member]
Real Estate Properties [Line Items]
Payments to Acquire Productive Assets					$ 238,700,000
Education Reportable Operating Segment [Member] | Education Property Member
Real Estate Properties [Line Items]
Number of properties acquired (in properties)					2
Proceeds from Sale of Property, Plant, and Equipment					$ 9,800,000
Gain on sale of real estate					1,900,000
Proceeds from sale of property, plant, and equipment tenant purchase option					44,800,000
Gain (Loss) on disposition of assets from tenant purchase option					$ 7,200,000
Education Reportable Operating Segment [Member] | early childhood education center [Member]
Real Estate Properties [Line Items]
Number of properties acquired (in properties)					7
Payments to Acquire Productive Assets					$ 38,300,000
Recreation Reportable Operating Segment [Member]
Real Estate Properties [Line Items]
Payments to Acquire Productive Assets					951,600,000
Recreation Reportable Operating Segment [Member] | Ski Resorts, Attractions and Family Entertainment Centers [Member]
Real Estate Properties [Line Items]
Payments to Acquire Productive Assets	$ 730,800,000				$ 730,788,000
Recreation Reportable Operating Segment [Member] | Other Recreation [Member]
Real Estate Properties [Line Items]
Number of properties acquired (in properties)					5
Payments to Acquire Productive Assets					$ 51,900,000
Recreation Reportable Operating Segment [Member] | fitness center [Member] [Domain]
Real Estate Properties [Line Items]
Payments to Acquire Productive Assets					10,700,000
Other Reportable Operating Segment [Member]
Real Estate Properties [Line Items]
Payments to Acquire Productive Assets					$ 1,000,000
Mortgage Receivable [Member] | Education Property Member
Real Estate Properties [Line Items]
Mortgage Notes, Additional Funding			$ 95,500,000
Common Stock [Member]
Real Estate Properties [Line Items]
Stock Issued During Period, Shares, Acquisitions | shares	8,851,264				8,851,264
Stock Issued During Period, Value, Acquisitions					$ 89,000