Investments (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Certificates of deposits	$ 6,700	$ 11,400
Certificates of deposit interest rate, lower range	0.35%
Certificates of deposit interest rate, upper range	0.60%
Investments held to maturity	$ 6,176	$ 15,987
Minimum [Member]
Schedule of Investments [Line Items]
Certificates of deposit maturity dates	6 months
Investments maturity dates	3 months
Maximum [Member]
Schedule of Investments [Line Items]
Certificates of deposit maturity dates	13 months
Investments maturity dates	13 months