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Leases - Narrative (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Lessor, Lease, Description [Line Items]    
Property, plant and equipment, net $ 119,324 $ 122,483
Accumulated depreciation $ 283,517 $ 288,971
Lessor, existence of option to extend true  
Option to extend true  
Operating lease income $ 674  
Variable lease income $ 199  
Option to terminate true  
Control Devices [Member]    
Lessor, Lease, Description [Line Items]    
Accumulated depreciation $ 7,637  
Lessor, option to extend The lease includes two optional extension terms of five years each.  
Extension terms 5 years  
Land [Member] | Control Devices [Member]    
Lessor, Lease, Description [Line Items]    
Property, plant and equipment, net $ 1,225  
Buildings and Improvements [Member] | Control Devices [Member]    
Lessor, Lease, Description [Line Items]    
Property, plant and equipment, net $ 9,635