Business Segment, Geographic and Major Customer Information - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 73,679	$ 87,942	$ 218,287	$ 257,346
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	58,183	73,796	169,991	211,242
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 15,496	$ 14,146	$ 48,296	$ 46,104