Annual report pursuant to Section 13 and 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING PRINCIPLES AND PRACTICES - Narrative (Details)

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SUMMARY OF SIGNIFICANT ACCOUNTING PRINCIPLES AND PRACTICES - Narrative (Details)
 1 Months Ended 3 Months Ended 12 Months Ended
Feb. 14, 2022
USD ($)
Oct. 03, 2021
USD ($)
Feb. 13, 2021
USD ($)
Oct. 04, 2019
USD ($)
Jul. 12, 2019
USD ($)
Jul. 01, 2019
USD ($)
Sep. 30, 2021
USD ($)
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Mar. 28, 2020
USD ($)
Dec. 31, 2021
USD ($)
segment
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Number of reportable segments | segment                     2    
Business acquisition purchase price paid in cash                     $ 0 $ 0 $ 28,907,000
Net cash provided by (used in) operating activities                     (5,530,000) 37,335,000 42,689,000
Net Gain on Sale of Businesses               $ 10,677,000 $ 0   10,677,000 0 78,801,000
Impairment charge   $ 0                 0 86,312,000 1,600,000
Research and development, design and related engineering                     $ 85,300,000 86,800,000 108,900,000
Cash and cash equivalents maturity period (in months)                     3 months    
Depreciation expense                     $ 12,700,000 13,300,000 13,700,000
Impairment charge to right-of-use                     0 691,000  
Long-lived asset impairment charge                         9,500,000
Equity investment impairment                     $ 0 3,493,000 5,000,000
Cumulative pretax loss position period                     3 years    
Cash dividends paid                     $ 0 0 0
United States Department Of Transportation | Grant                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
USDOT grant receivable amount             $ 14,700,000 7,300,000     7,300,000    
Second installment to be received               5,200,000     5,200,000    
Portion of grant received             $ 7,400,000            
Revenue recognized included in contract liability balance                     8,700,000    
Unearned portion of the AMPJ award               6,000,000     6,000,000    
Federal                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Valuation allowance, deferred tax asset, increase (decrease)                 14,100,000   6,000,000 23,300,000  
Foreign Tax Authority                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Valuation allowance, deferred tax asset, increase (decrease)                     $ 1,300,000    
Disposed of by Sale | Airfield Lighting Product Line                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Proceeds from sale         $ 1,000,000                
Percentage of revenue (as a percentage)         1.00%                
Pre-tax loss on sale         $ 1,300,000                
Test Systems                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Impairment charge                       0  
Test Systems | Held for Sale                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Contingent earn-outs     $ 10,700,000                    
Test Systems | Held for Sale | Subsequent Event                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Contingent earn-outs $ 11,200,000                        
Aerospace                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Impairment charge                   $ 86,300,000   86,312,000  
Intangible asset impairment charge                         $ 6,200,000
Building | Minimum                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Property, plant and equipment, useful life (in years)                     25 years    
Building | Maximum                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Property, plant and equipment, useful life (in years)                     40 years    
Machinery and Equipment | Minimum                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Property, plant and equipment, useful life (in years)                     4 years    
Machinery and Equipment | Maximum                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Property, plant and equipment, useful life (in years)                     10 years    
Freedom Communication Technologies, Inc.                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Business acquisition purchase price paid in cash           $ 21,800,000              
Cash acquired           $ 600,000              
Diagnosys Test Systems Limited                          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                          
Cash purchase price       $ 7,000,000                  
Financial liabilities carried at fair value       $ 2,500,000       $ 0 $ 2,200,000   $ 0 $ 2,200,000