Revenue - Revenue Performance Obligations (Details) - USD ($) $ in Thousands |
3 Months Ended | ||
|---|---|---|---|
Mar. 30, 2018 |
Jan. 01, 2018 |
Dec. 31, 2017 |
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |||
| Funded backlog | $ 723,000 | $ 1,621 | $ 719,000 |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-03-31 | |||
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |||
| Revenue, performance obligation, percentage | 90.00% | ||
| Revenue,expected performance obligation, percentage | 9 months | ||
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 | |||
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |||
| Revenue, performance obligation, percentage | 10.00% | ||
| Revenue,expected performance obligation, percentage | 1 year |