Segments and Major Customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Financial information of business segments
Revenues	$ 56,458	$ 94,720	$ 102,884	$ 192,071
Segment operating expenses	40,699	44,669	82,064	86,058
Segment reconciling items	(35,746)	(41,807)	(84,420)	(84,335)
Operating income (loss)	(19,987)	8,244	(63,600)	21,678
Interest and other income (expense), net	3,615	(3,132)	8,310	(6,184)
Income (Loss) before income taxes	(16,372)	5,112	(55,290)	15,494
MID Segment
Financial information of business segments
Revenues	34,976	67,402	68,965	137,997
Segment operating expenses	22,597	23,801	45,546	44,056
Segment Operating Income (Loss)	12,379	43,601	23,419	93,941
RSD Segment
Financial information of business segments
Revenues	21,482	23,366	31,478	46,571
Segment operating expenses	14,893	12,214	27,678	24,613
Segment Operating Income (Loss)	6,589	11,152	3,800	21,958
Other
Financial information of business segments
Revenues	0	3,952	2,441	7,503
Segment operating expenses	3,209	8,654	8,840	17,389
Segment Operating Income (Loss)	(3,209)	(4,702)	(6,399)	(9,886)
Operating Segments [Member]
Financial information of business segments
Segment Operating Income (Loss)	$ 15,759	$ 50,051	$ 20,820	$ 106,013