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Employee Benefit Plans - Additional Information (Detail) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]      
Highest credit service of a specified period for benefits on employees contributions 5 years    
Last credit service period for benefits on employees compensation 10 years    
Fair value of plan assets $ 1,933,063,000 $ 1,595,679,000  
Genuine Parts Company common stock included in equity securities 167,788,000 128,236,000  
Genuine Parts Company common stock as a percentage of total plan assets 8.70% 8.00%  
Dividend payments on Genuine Parts Company common stock received by plan 4,336,000 3,994,000  
Pension benefits expected to be paid from employer assets in 2014 5,978,000    
Defined Contribution Plans [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Matching contribution to be received by pension plan participants of a specified percentage of employee's salary 20.00%    
First percentage of employee's salary out of which matching contribution will be made 6.00%    
Matching contribution to be received by other employees of a specified percentage of other employees salary 100.00%    
First percentage of other employee's salary out of which matching contribution will be made 5.00%    
Matching contribution to be received by all employees of a specified percentage of employees' salary after 2013 100.00%    
First percentage of all employees' salary out of which matching contribution will be made after 2013 5.00%    
Total defined contribution plans expense 43,236,000 43,155,000 38,773,000
United States Pension Plan of US Entity, Defined Benefit [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Benefit obligations 1,838,810,000 1,955,414,000  
Fair value of plan assets 1,745,769,000 1,425,047,000  
Pension Benefits [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Curtailment gain   23,507,000  
Benefit obligations 2,035,185,000 2,165,692,000 1,958,399,000
Total accumulated benefit obligations 2,017,619,000 2,112,134,000  
Fair value of plan assets $ 1,933,063,000 $ 1,595,679,000 $ 1,470,030,000
Expected rate of return on plan assets for measuring 2014 pension cost or income 7.85%    
S&P 500 Index [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Passive portfolio benchmark 49.00%    
Russell Mid Cap Index [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Passive portfolio benchmark 5.00%    
Russell 2000 Index [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Passive portfolio benchmark 8.00%    
MSCI EAFE Index [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Passive portfolio benchmark 5.00%    
DJ Global Moderate Index [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Passive portfolio benchmark 5.00%    
BarCap U.S. Govt/Credit [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Passive portfolio benchmark 28.00%