Investments (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Schedule of Investments [Line Items]
Certificates of deposits	$ 6,200	$ 12,000
Certificates of deposit interest rate, lower range	0.45%
Certificates of deposit interest rate, upper range	0.90%
Investments held to maturity	$ 20,518	$ 17,483
Minimum [Member]
Schedule of Investments [Line Items]
Certificates of deposit maturity dates	1 month
Investments maturity dates	1 month
Maximum [Member]
Schedule of Investments [Line Items]
Certificates of deposit maturity dates	10 months
Investments maturity dates	9 months