Revenue - Additional Information (Details) contract in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Oct. 01, 2017 USD ($)	Sep. 30, 2018 USD ($) contract	Oct. 01, 2017 USD ($)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Number of active contracts | contract			10
Revenue recognized in contract liability balance | $	$ 875	$ 982	$ 3,500	$ 3,900
Transferred over Time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, percentage from products and services transferred to customers	74.00%	70.00%	75.00%	70.00%
Transferred at Point in Time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, percentage from products and services transferred to customers	26.00%	30.00%	25.00%	30.00%