Quarterly report pursuant to Section 13 or 15(d)

Business Segments and Customer Information - Major Customers (Details)

v3.19.1
Business Segments and Customer Information - Major Customers (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Revenue, Major Customer [Line Items]    
Revenues $ 169,919 $ 176,897
USPS    
Revenue, Major Customer [Line Items]    
Revenues 42,683 44,031
U.S. Navy    
Revenue, Major Customer [Line Items]    
Revenues 20,605 42,585
U.S. Army    
Revenue, Major Customer [Line Items]    
Revenues 36,719 42,787
U.S. Air Force    
Revenue, Major Customer [Line Items]    
Revenues 5,377 2,281
Total - DoD    
Revenue, Major Customer [Line Items]    
Revenues 62,701 87,653
Commercial aviation    
Revenue, Major Customer [Line Items]    
Revenues 48,475 31,535
Other commercial    
Revenue, Major Customer [Line Items]    
Revenues 5,084 3,588
Total - Commercial    
Revenue, Major Customer [Line Items]    
Revenues 53,559 35,123
Other government    
Revenue, Major Customer [Line Items]    
Revenues $ 10,976 $ 10,090
Customer Concentration Risk | Sales Revenue, Net    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 100.00% 100.00%
Customer Concentration Risk | Sales Revenue, Net | USPS    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 25.10% 24.90%
Customer Concentration Risk | Sales Revenue, Net | U.S. Navy    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 12.10% 24.10%
Customer Concentration Risk | Sales Revenue, Net | U.S. Army    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 21.60% 24.20%
Customer Concentration Risk | Sales Revenue, Net | U.S. Air Force    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 3.20% 1.30%
Customer Concentration Risk | Sales Revenue, Net | Total - DoD    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 36.90% 49.60%
Customer Concentration Risk | Sales Revenue, Net | Commercial aviation    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 28.50% 17.80%
Customer Concentration Risk | Sales Revenue, Net | Other commercial    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 3.00% 2.00%
Customer Concentration Risk | Sales Revenue, Net | Total - Commercial    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 31.50% 19.80%
Customer Concentration Risk | Sales Revenue, Net | Other government    
Revenue, Major Customer [Line Items]    
Percentage of revenue by customer 6.50% 5.70%