Derivative and Hedging (Effects of Cash Flow Hedges) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Investment Income (Expense) | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts of expense line items presented in the statement of financial performance in which the effects of cash flow hedges are recorded	$ (16)