Purchased Intangible Assets and Goodwill (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization	$ 1,039	$ 1,039	$ 1,100
Definite life intangible assets, weighted average remaining life	3 years 3 months 11 days
Minimum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Definite life intangible assets, amortization period	13 years
Maximum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Definite life intangible assets, amortization period	20 years