Annual report pursuant to Section 13 and 15(d)

Business Segments and Customer Information, Major Customers (Details)

v3.8.0.1
Business Segments and Customer Information, Major Customers (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 760,113 $ 691,790 $ 533,982
Percentage of revenue by customer 100.00% 100.00% 100.00%
U.S. Postal Service      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 180,205 $ 181,215 $ 184,876
Percentage of revenue by customer 23.70% 26.20% 34.60%
U.S. Navy      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 206,644 $ 190,155 $ 98,887
Percentage of revenue by customer 27.20% 27.50% 18.50%
U.S. Army      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 188,462 $ 139,764 $ 80,086
Percentage of revenue by customer 24.80% 20.20% 15.00%
U.S. Air Force      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 7,123 $ 3,482 $ 3,558
Percentage of revenue by customer 0.90% 0.50% 0.70%
Total - DoD      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 402,229 $ 333,401 $ 182,531
Percentage of revenue by customer 52.90% 48.20% 34.20%
Commercial Aviation      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 126,960 $ 131,067 $ 119,729
Percentage of revenue by customer 16.70% 19.00% 22.40%
Other Commercial      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 12,498 $ 10,721 $ 4,653
Percentage of revenue by customer 1.70% 1.50% 0.90%
Total - Commercial      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 139,458 $ 141,788 $ 124,382
Percentage of revenue by customer 18.40% 20.50% 23.30%
Other Government      
Revenue, Major Customer [Line Items]      
Revenue, by customer $ 38,221 $ 35,386 $ 42,193
Percentage of revenue by customer 5.00% 5.10% 7.90%