Real Estate Loans Receivable (Textuals) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017
Financing Receivable, Modifications [Line Items]
Allowance for loan losses	$ 68,372,000		$ 68,372,000	$ 5,406,000
Real estate loans with outstanding balances			$ 2,598,000
Genesis Healthcare Loans [Member] | Triple Net
Financing Receivable, Modifications [Line Items]
Provision For Loan And Lease Losses Real Estate Excluding Write Off	$ 62,966,000	$ 6,935,000