Business Segment, Geographic and Major Customer Information - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 87,030	$ 105,318	$ 169,404	$ 207,893
U.S. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	73,250	91,691	137,446	179,022
Other countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 13,780	$ 13,627	$ 31,958	$ 28,871