Mortgage Loans on Real Estate (Allowance for Loan Losses Rollforward) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning allowance balance			$ (7,518)
Ending allowance balance	$ (6,326)		(6,326)
Specific Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning allowance balance	(696)	$ (1,327)	(1,418)	$ (1,327)
Charge-offs	0	0	0	0
Recoveries	0	0	722	0
Change in provision for credit losses	0	(722)	0	(722)
Ending allowance balance	(696)	(2,049)	(696)	(2,049)
General Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning allowance balance	(5,800)	(6,800)	(6,100)	(7,100)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Change in provision for credit losses	170	1,000	470	1,300
Ending allowance balance	$ (5,630)	$ (5,800)	$ (5,630)	$ (5,800)