Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt - Swaps (Details)

v3.10.0.1
Long-Term Debt - Swaps (Details)
$ in Thousands
Feb. 20, 2015
USD ($)
contract
Sep. 30, 2018
USD ($)
item
Dec. 31, 2017
USD ($)
Derivative [Line Items]      
Number of interest rate swap agreements | contract 3    
Inventories - truck chassis floor plan   $ 9,495 $ 7,711
Interest rate swap      
Derivative [Line Items]      
Negative fair value   $ 935 2,178
Number of financial institutions for which the entity is exposed to counterparty credit risk | item   1  
Interest rate swap | Accrued Expenses and Other Current Liabilities      
Derivative [Line Items]      
Negative fair value   $ 7 597
Interest rate swap | Other Noncurrent Liabilities      
Derivative [Line Items]      
Negative fair value   $ 942 $ 1,581
Interest Rate Swap Effective 31 December 2015 through 29 March 2018      
Derivative [Line Items]      
Notional amount $ 45,000    
Interest rate   6.105%  
Interest Rate Swap Effective 31 December 2015 through 29 March 2018 | London Interbank Offered Rate (LIBOR)      
Derivative [Line Items]      
Interest rate added to variable rate (as a percent)   3.00%  
LIBOR floor (as a percent)   1.00%  
Interest Rate Swap Effective 29 March 2018 through 31 March 2020      
Derivative [Line Items]      
Notional amount 90,000    
Interest rate   6.916%  
Interest Rate Swap Effective 29 March 2018 through 31 March 2020 | London Interbank Offered Rate (LIBOR)      
Derivative [Line Items]      
Interest rate added to variable rate (as a percent)   3.00%  
LIBOR floor (as a percent)   1.00%  
Interest Rate Swap Effective 31 March 2020 through 30 June 2021      
Derivative [Line Items]      
Notional amount $ 135,000    
Interest rate   7.168%  
Interest Rate Swap Effective 31 March 2020 through 30 June 2021 | London Interbank Offered Rate (LIBOR)      
Derivative [Line Items]      
Interest rate added to variable rate (as a percent)   3.00%  
LIBOR floor (as a percent)   1.00%  
Interest rate swap effective December 31, 2018 through June 30, 2021      
Derivative [Line Items]      
Notional amount   $ 50  
Interest rate   2.613%  
Interest rate swap effective June 30, 2021 through December 10, 2021      
Derivative [Line Items]      
Notional amount   $ 150  
Interest rate swap effective June 30, 2021 through December 10, 2021 | Maximum      
Derivative [Line Items]      
Interest rate   2.793%