Investments (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Schedule of Available-for-sale Securities [Line Items]
Reclassification of net unrealized losses from accumulated other comprehensive income (AOCI) to retained earnings		$ 0
Accounting Standards Update No. 2016-01 [Member]
Schedule of Available-for-sale Securities [Line Items]
Reclassification of net unrealized losses from accumulated other comprehensive income (AOCI) to retained earnings		$ 7
Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Treasury Bills, term	1 month
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Treasury Bills, term	6 months