Business Segment, Geographic and Major Customer Information (Revenue by Geographic Location) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue by geographic location
Revenue	$ 77,014	$ 87,942	$ 87,030	$ 82,373	$ 124,503	$ 116,761	$ 105,318	$ 102,575	$ 334,359	$ 449,157	$ 371,065
U.S. [Member]
Revenue by geographic location
Revenue									273,624	370,087	319,649
Other countries [Member]
Revenue by geographic location
Revenue									$ 60,735	$ 79,070	$ 51,416