Annual report pursuant to Section 13 and 15(d)

Description of Business and Summary of Significant Accounting Policies - Additional Information (Details)

v3.19.3.a.u2
Description of Business and Summary of Significant Accounting Policies - Additional Information (Details)
 12 Months Ended
Dec. 31, 2019
USD ($)
Dealerships
Brand
Collision
State
Store
Segment
reporting_unit
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Jan. 01, 2019
USD ($)
Jan. 01, 2018
USD ($)
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Number of operating segments | Segment 2        
Number of new vehicle dealerships | Dealerships 99        
Number of states | State 12        
Number of different brands of cars and light trucks | Brand 21        
Number of collision repair centers | Collision 15        
Operating lease liabilities $ 347,483,000     $ 419,500,000  
ROU assets 337,842,000 $ 0   $ 387,970,000  
Book overdraft position   0      
Revenue allowances for commission reserves 32,000,000.0 25,800,000      
Amount recognized for floor plan assistance $ 41,500,000 42,200,000 $ 45,300,000    
Term for funding of finance contracts 10 days        
Contracts in transit included in receivables, net $ 230,900,000 227,800,000      
Receivables, net $ 432,742,000 438,186,000     $ 486,716,000
Number of reporting units | reporting_unit 2        
Goodwill $ 475,791,000 509,592,000 525,780,000    
Insurance reserves 23,100,000 22,900,000      
Concentrations of credit risk with respect to receivables are limited primarily to receivables from automobile manufacturers 94,800,000 93,800,000      
Advertising expense 60,800,000 63,100,000 61,600,000    
Cooperative manufacturer credits advertising expenses $ 25,300,000 26,700,000 $ 26,000,000.0    
Number of reportable Segment | Segment 2        
Financial institutions          
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Concentrations of credit risk with respect to receivables are limited primarily to receivables from financial institutions $ 258,700,000        
Franchise assets          
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Franchise asset impairment charge   2,100,000      
Continuing operations | Franchise assets          
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Franchise asset impairment charge $ 0 $ 2,100,000      
Dealership          
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Percentage of dealership that is accounted for under the equity method 50.00%        
Franchised dealerships          
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Goodwill $ 415,800,000        
EchoPark          
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Goodwill $ 60,000,000.0        
Franchised dealerships          
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Number of Stores | Store 86        
EchoPark          
Description Of Business And Summary Of Significant Accounting Policies [Line Items]          
Number of Stores | Store 9