Goodwill and Intangible Assets - Estimated Future Amortized Intangible Expense by Purchased Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Acquired Indefinite-lived Intangible Assets [Line Items]
2019	$ 8,338
2020	3,979
2021	500
Total future amortization expense	12,817	$ 21,279
Cost of Sales [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
2019	5,180
2020	951
2021	0
Total future amortization expense	6,131
Operating expense [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
2019	3,158
2020	3,028
2021	500
Total future amortization expense	$ 6,686