Mortgage Loans on Real Estate (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) portfolio_segment	Dec. 31, 2016 USD ($)
Mortgage Loans on Real Estate [Abstract]
Number of portfolio segments that make up financing receivables | portfolio_segment	1
Impaired mortgage loans, workout terms, interest only payments, six month terms	6 months
Impaired mortgage loans, workout terms, interest only payments, twelve month terms	12 months
Impaired mortgage loans, workout terms, cash flow sweep, number of months	12 months
Number of days past due, non-accrual status	90 days
Non-accrual loans	$ 2,200	$ 0
Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Number of days past due, delinquent status	60 days
Commercial Real Estate Portfolio Segment [Member]
Mortgage Loans on Real Estate [Line Items]
Commitments outstanding	$ 62,000