Revenues - Narrative (Details) - USD ($) $ in Thousands	Sep. 29, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Contract with customer, deferred revenues	$ 99,210	$ 113,347	$ 90,839	$ 104,412
Contract with customer, deferred revenues, current	86,500
Contract with customer, deferred revenues, noncurrent	12,700
Deferred sales commission	$ 3,000		$ 2,300