Employee Benefit Plans - Fair Value of Plan Assets (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	$ 1,595,679,000	$ 1,470,030,000
Common stocks - mutual funds - equity [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	342,846,000	348,909,000
Other stocks [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	608,017,000	546,995,000
Short-term Investments [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	37,626,000	38,968,000
Cash and equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	45,719,000	16,888,000
Government bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	166,413,000	145,966,000
Corporate bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	127,824,000	127,698,000
Asset-backed and mortgage-backed securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	24,077,000	21,441,000
Other-international [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	10,188,000	12,084,000
Municipal bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	532,000	593,000
Municipal funds-fixed income [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	101,578,000	87,052,000
Cash surrender value of life insurance policies [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	2,623,000
Genuine Parts Company Common Stock [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	128,236,000	123,436,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	1,247,339,000	1,153,614,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common stocks - mutual funds - equity [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	342,846,000	348,909,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other stocks [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	608,017,000	546,995,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	37,626,000	38,968,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash and equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	45,719,000	16,888,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Government bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	74,707,000	66,334,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Asset-backed and mortgage-backed securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other-international [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	10,188,000	12,084,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal funds-fixed income [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash surrender value of life insurance policies [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Genuine Parts Company Common Stock [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	128,236,000	123,436,000
Significant Observable Inputs (Level 2) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	345,717,000	316,416,000
Significant Observable Inputs (Level 2) [Member] | Common stocks - mutual funds - equity [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Other stocks [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Cash and equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Government bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	91,706,000	79,632,000
Significant Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	127,824,000	127,698,000
Significant Observable Inputs (Level 2) [Member] | Asset-backed and mortgage-backed securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	24,077,000	21,441,000
Significant Observable Inputs (Level 2) [Member] | Other-international [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Municipal bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	532,000	593,000
Significant Observable Inputs (Level 2) [Member] | Municipal funds-fixed income [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	101,578,000	87,052,000
Significant Observable Inputs (Level 2) [Member] | Cash surrender value of life insurance policies [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Genuine Parts Company Common Stock [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	2,623,000
Significant Unobservable Inputs (Level 3) [Member] | Common stocks - mutual funds - equity [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Other stocks [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Cash and equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Government bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Asset-backed and mortgage-backed securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Other-international [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Municipal bonds [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Municipal funds-fixed income [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Cash surrender value of life insurance policies [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets	2,623,000
Significant Unobservable Inputs (Level 3) [Member] | Genuine Parts Company Common Stock [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of assets