Business Segments and Customer Information Business Segments and Customer Information, Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 691,790	$ 533,982	$ 424,071
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	638,726	481,466	422,519
Other Countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 53,064	$ 52,516	$ 1,552