Annual report pursuant to Section 13 and 15(d)

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

v3.6.0.2
Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2016
USD ($)
Dealerships
State
Brand
Collision
Store
Franchise
Segment
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Description Of Business And Summary Of Significant Accounting Policies [Line Items]      
Number of dealerships | Dealerships 116    
Number of states | State 13    
Number of different brands of cars and light trucks | Brand 25    
Number of collision repair centers | Collision 18    
Noncurrent deferred tax asset included in other assets $ 2,400,000 $ 2,800,000  
Net long-term deferred tax liability 76,447,000 73,322,000  
Current deferred tax asset included in other current assets 0 13,600,000  
Current deferred tax liability included in other accrued liabilities 0 100,000  
Book overdraft position 8,000,000 38,500,000  
Revenue allowances for commission reserves 19,200,000 17,000,000  
Amount recognized for continue operation $ 45,000,000 42,100,000 $ 39,700,000
Term for funding of finance contracts 10 days    
Contracts in transit included in receivables, net $ 236,400,000 196,300,000  
Number of reporting units | Franchise 2    
Goodwill $ 472,437,000 471,493,000 475,929,000
Insurance reserves 22,700,000 24,900,000  
Concentrations of credit risk with respect to receivables are limited primarily to automobile manufacturers 92,800,000 90,300,000  
Deposits 10,000,000 74,000,000  
Reduction in interest expense 600,000 1,500,000 2,100,000
Advertising expense 61,700,000 61,600,000 57,400,000
Cooperative manufacturer credits advertising expenses $ 26,200,000 24,200,000 23,400,000
Number of reportable Segment | Segment 2    
Financial Institutions [Member]      
Description Of Business And Summary Of Significant Accounting Policies [Line Items]      
Concentrations of credit risk with respect to receivables are limited primarily to financial institutions $ 265,300,000 221,600,000  
Franchise Assets [Member]      
Description Of Business And Summary Of Significant Accounting Policies [Line Items]      
Franchise asset impairment charges 0 3,300,000  
Continuing Operations [Member] | Franchise Assets [Member]      
Description Of Business And Summary Of Significant Accounting Policies [Line Items]      
Franchise asset impairment charges 0 $ 900,000 $ 2,200,000
Accounting Standards Update 2015-17 [Member]      
Description Of Business And Summary Of Significant Accounting Policies [Line Items]      
Noncurrent deferred tax asset included in other assets 2,400,000    
Net long-term deferred tax liability $ 76,400,000    
Dealership [Member]      
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 [Member]      
Description Of Business And Summary Of Significant Accounting Policies [Line Items]      
Number of stores | Store 107    
Echo Park [Member]      
Description Of Business And Summary Of Significant Accounting Policies [Line Items]      
Number of stores | Store 5