Development Project Costs, Cash Collateral for Deposit Bond and Cash for Development Projects (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Feb. 29, 2016	Dec. 31, 2015
Development Costs [Line Items]
Capitalized project development costs	$ 437,200		$ 437,200			$ 202,400
Interest Expense			18,200
Project Development Costs Incurred			248,600	$ 150,300
Capitalized Project Development Costs, Period Increase			234,800	141,000
Development Projects costs	5,196	$ 3,159	13,881	9,382
Deposit Assets	$ 20,000		$ 20,000				$ 15,000
Deposit Asset, Percent of Minimum Capital Investment Expended for Deposit Return	85.00%		85.00%
Restricted Cash and Cash Equivalents, Noncurrent	$ 235,057		$ 235,057			26,384
Cash and Cash Equivalents, at Carrying Value	6,213	$ 9,071	6,213	9,071		11,012		$ 6,412
Land Lease Expense [Member]
Development Costs [Line Items]
Project Development Costs Incurred			8,000	7,800
Salary and Related Benefits [Member]
Development Costs [Line Items]
Project Development Costs Incurred			2,405
Bank Charges [Member]
Development Costs [Line Items]
Project Development Costs Incurred			1,455
Pre-opening Expense [Member]
Development Costs [Line Items]
Project Development Costs Incurred			361	583
Professional Services [Member]
Development Costs [Line Items]
Project Development Costs Incurred			482	305
Property Tax Expense [Member]
Development Costs [Line Items]
Project Development Costs Incurred			482	412
Insurance Expense [Member]
Development Costs [Line Items]
Project Development Costs Incurred			428	$ 339
Selling and Marketing Expense [Member]
Development Costs [Line Items]
Project Development Costs Incurred			247
Transferable Subscription Rights [Member]
Development Costs [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent						$ 26,400
Scenario, Forecast [Member]
Development Costs [Line Items]
Deposit Assets					$ 30,100
Development Projects [Member] | Transferable Subscription Rights [Member]
Development Costs [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	235,100		235,100
Cash and Cash Equivalents, at Carrying Value	112,700		112,700
Short-term Investments	$ 122,400		$ 122,400