Inventories - Narrative (Details) - USD ($) $ in Thousands  | 
Dec. 31, 2019  | 
Dec. 31, 2018  | 
|---|---|---|
| Inventory [Line Items] | ||
| Reserve for inventory valuation | $ 33,600 | $ 20,800 | 
| Percentage of reserve for inventory valuation | 18.70% | 12.00% | 
| Held for Sale | Test Systems | ||
| Inventory [Line Items] | ||
| Inventories | $ 14,385 | 
| X | ||||||||||
- Definition Inventory valuation reserves as percentage of gross inventory. No definition available. 
  | 
| X | ||||||||||
- Definition Amount classified as inventory attributable to disposal group held for sale or disposed of. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
  | 
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
  | 
| X | ||||||||||
- Definition Amount of valuation reserve for inventory. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
  | 
| X | ||||||||||
- Details 
  | 
| X | ||||||||||
- Details 
  |