Business Segments and Customer Information - Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 195,271	$ 198,326	$ 189,111	$ 169,919	$ 180,996	$ 168,931	$ 170,394	$ 176,897	$ 752,627	$ 697,218	$ 760,113
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									659,451	647,168	708,474
Other Countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 93,176	$ 50,050	$ 51,639