Details of Selected Balance Sheet Accounts - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of intangible assets, net
Gross Amount	$ 36,934	$ 37,469
Accumulated Amortization	(33,831)	(32,659)
Net	3,103	4,810
Amortization expenses	1,700	1,900	$ 2,500
Customer relationships [Member]
Summary of intangible assets, net
Gross Amount	36,934	37,469
Accumulated Amortization	(33,831)	(32,659)
Net	$ 3,103	$ 4,810