Segments and Major Customers (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial information of business segments
Revenue	$ 101,891	$ 99,134	$ 94,720	$ 97,351	$ 97,559	$ 89,855	$ 76,501	$ 72,682	$ 393,096	$ 336,597	$ 296,278
Segment operating expenses									169,914	150,712	108,983
Segment operating income (loss)									223,182	185,885	187,295
Reconciling items									(168,775)	(152,243)	(115,875)
Operating income (loss)	$ 15,719	$ 17,010	$ 8,244	$ 13,434	$ 524	$ 11,816	$ 12,008	$ 9,294	54,407	33,642	71,420
Interest and other income (expense), net									(13,418)	(11,005)	(11,189)
Income before income taxes									40,989	22,637	60,231
MID
Financial information of business segments
Revenue									280,704	239,843	221,968
Segment operating expenses									86,044	68,460	47,780
Segment operating income (loss)									194,660	171,383	174,188
RSD
Financial information of business segments
Revenue									96,663	76,175	50,497
Segment operating expenses									50,010	51,855	29,056
Segment operating income (loss)									46,653	24,320	21,441
Other
Financial information of business segments
Revenue									15,729	20,579	23,813
Segment operating expenses									33,860	30,397	32,147
Segment operating income (loss)									$ (18,131)	$ (9,818)	$ (8,334)