Schedule IV - Mortgage Loans on Real Estate (Reconciliation of mortgage loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of mortgage loans:
Balance at beginning of year	$ 249,071	$ 306,120	$ 485,735
Additions:
New mortgage loans	0	25,290	6,706
Draws on existing loans	45,961	36,458	58,224
Total additions	45,961	61,748	64,930
Deductions:
Collections of principal	(87,249)	(116,905)	(180,135)
Loan balance transferred to non real estate loans receivable	(64,040)	0	0
Change in allowance for loan losses and charge-offs	0	0	(71,535)
Total deductions	(151,289)	(116,905)	(251,670)
Change in balance due to foreign currency translation	1,944	(1,892)	7,125
Balance at end of year	$ 145,686	$ 249,071	$ 306,120