Employee Benefit Plans (Details 2) (USD $)																																																																																																	12 Months Ended
Employee Benefit Plans (Details 2) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Common stocks - mutual funds - equity [Member]	Dec. 31, 2010 Common stocks - mutual funds - equity [Member]	Dec. 31, 2011 Common stocks - mutual funds - equity [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Common stocks - mutual funds - equity [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Common stocks - mutual funds - equity [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Common stocks - mutual funds - equity [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Common stocks - mutual funds - equity [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Common stocks - mutual funds - equity [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Genuine Parts Company [Member]	Dec. 31, 2010 Genuine Parts Company [Member]	Dec. 31, 2011 Genuine Parts Company [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Genuine Parts Company [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Genuine Parts Company [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Genuine Parts Company [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Genuine Parts Company [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Genuine Parts Company [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Other stocks [Member]	Dec. 31, 2010 Other stocks [Member]	Dec. 31, 2011 Other stocks [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Other stocks [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Other stocks [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Other stocks [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Other stocks [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Other stocks [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Short-term investments [Member]	Dec. 31, 2010 Short-term investments [Member]	Dec. 31, 2011 Short-term investments [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Short-term investments [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Short-term investments [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Short-term investments [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Short-term investments [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Short-term investments [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Cash and equivalents [Member]	Dec. 31, 2010 Cash and equivalents [Member]	Dec. 31, 2011 Cash and equivalents [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Cash and equivalents [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Cash and equivalents [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Cash and equivalents [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Cash and equivalents [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Cash and equivalents [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Government bonds [Member]	Dec. 31, 2010 Government bonds [Member]	Dec. 31, 2011 Government bonds [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Government bonds [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Government bonds [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Government bonds [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Government bonds [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Government bonds [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Corporate bonds [Member]	Dec. 31, 2010 Corporate bonds [Member]	Dec. 31, 2011 Corporate bonds [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Corporate bonds [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Corporate bonds [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Corporate bonds [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Corporate bonds [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Corporate bonds [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Asset-backed and mortgage-backed securities [Member]	Dec. 31, 2010 Asset-backed and mortgage-backed securities [Member]	Dec. 31, 2011 Asset-backed and mortgage-backed securities [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Asset-backed and mortgage-backed securities [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Asset-backed and mortgage-backed securities [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Asset-backed and mortgage-backed securities [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Asset-backed and mortgage-backed securities [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Asset-backed and mortgage-backed securities [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Other-international [Member]	Dec. 31, 2010 Other-international [Member]	Dec. 31, 2011 Other-international [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Other-international [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Other-international [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Other-international [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Other-international [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Other-international [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Municipal bonds [Member]	Dec. 31, 2010 Municipal bonds [Member]	Dec. 31, 2011 Municipal bonds [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Municipal bonds [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Municipal bonds [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Municipal bonds [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Municipal bonds [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Municipal bonds [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Mutual funds-fixed income [Member]	Dec. 31, 2010 Mutual funds-fixed income [Member]	Dec. 31, 2011 Mutual funds-fixed income [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2010 Mutual funds-fixed income [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	Dec. 31, 2011 Mutual funds-fixed income [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Mutual funds-fixed income [Member] Significant Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Mutual funds-fixed income [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Mutual funds-fixed income [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Target asset allocation 2012 [Member]
Asset allocations for Company's funded pension plans
Target Allocation Percentage of Assets, Equity Securities																																																																																																	69.00%
Equity securities	69.00%	70.00%
Target Allocation Percentage of Assets, Debt Securities																																																																																																	31.00%
Debt securities	31.00%	30.00%
Target Allocation Percentage of Assets, Total																																																																																																	100.00%
Asset allocation, Total	100.00%	100.00%
Fair Value of Assets
Fair value of assets	$ 1,470,030,000	$ 1,439,711,000	$ 1,153,614,000	$ 1,135,288,000	$ 316,416,000	$ 304,423,000	$ 0	$ 0	$ 348,909,000	$ 353,347,000	$ 348,909,000	$ 353,347,000	$ 0	$ 0	$ 0	$ 0	$ 123,436,000	$ 103,549,000	$ 123,436,000	$ 103,549,000	$ 0	$ 0	$ 0	$ 0	$ 546,995,000	$ 551,516,000	$ 546,995,000	$ 551,516,000	$ 0	$ 0	$ 0	$ 0	$ 38,968,000	$ 38,126,000	$ 38,968,000	$ 38,126,000	$ 0	$ 0	$ 0	$ 0	$ 16,888,000	$ 26,976,000	$ 16,888,000	$ 26,976,000	$ 0	$ 0	$ 0	$ 0	$ 145,966,000	$ 105,764,000	$ 66,334,000	$ 48,191,000	$ 79,362,000	$ 57,573,000	$ 0	$ 0	$ 127,698,000	$ 122,749,000	$ 0	$ 0	$ 127,698,000	$ 122,749,000	$ 0	$ 0	$ 21,441,000	$ 32,271,000	$ 0	$ 0	$ 21,441,000	$ 32,271,000	$ 0	$ 0	$ 12,084,000	$ 13,583,000	$ 12,084,000	$ 13,583,000	$ 0	$ 0	$ 0	$ 0	$ 593,000	$ 1,914,000	$ 0	$ 0	$ 593,000	$ 1,914,000	$ 0	$ 0	$ 87,052,000	$ 89,916,000	$ 0	$ 0	$ 87,052,000	$ 89,916,000	$ 0	$ 0

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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