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Revenue (Narratives) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Dec. 31, 2018
Revenue from Contract with Customer [Abstract] |  |  |  |  |
Revenue remaining performance obligation | $ 194,083 |  | $ 194,083 |  |
Disaggregation of Revenue |  |  |  |  |
Total net sales | 154,276 | $ 167,094 | 505,678 | $ 462,438 |
Contract with customer, assets | 34,792 |  | 34,792 |  | $ 26,692
Contract with customer, liability | 3,343 |  | 3,343 |  | $ 1,505
Contract assets transferred to receivables |  |  | 22,320 |  |
Cash proceeds from liability contract |  |  | 3,100 |  |
Revenue recognized from contract liability | $ 194 | $ 406 | $ 1,460 | $ 1,146 |
Over time |  |  |  |  |
Disaggregation of Revenue |  |  |  |  |
Customer revenue transferred over-time (percentage) | 33.40% | 26.80% | 28.10% | 25.20% |
Total net sales | $ 51,519 | $ 44,735 | $ 141,862 | $ 116,433 |
Over time | Performance Based |  |  |  |  |
Disaggregation of Revenue |  |  |  |  |
Total net sales | 37,488 | 33,225 | 104,309 | 87,369 |
Over time | Delivery Based |  |  |  |  |
Disaggregation of Revenue |  |  |  |  |
Total net sales | $ 14,031 | $ 11,510 | $ 37,553 | $ 29,064 |
Point in time |  |  |  |  |
Disaggregation of Revenue |  |  |  |  |
Customer revenue transferred over-time (percentage) | 66.60% | 73.20% | 71.90% | 74.80% |
Total net sales | $ 102,757 | $ 122,359 | $ 363,816 | $ 346,005 |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01 |  |  |  |  |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction |  |  |  |  |
Revenue remaining performance obligation (percentage) | 7.70% |  | 7.70% |  |
Performance obligations expected to be satisfied, expected timing | 12 months |  | 12 months |  |

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