Employee Benefit Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	$ 276,274	$ 2,223,879	$ 2,233,079
Common stocks — mutual funds — equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	55,543	54,256
Genuine Parts Company common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	176,640
Other stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	76,937	72,749
Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	374	1,422
Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	18,878	12,365
Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	52,362	52,381
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	72,179	66,321
Mutual funds-fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		201,247
Short Term Collective Trust
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		345,064
Options and futures
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		1,241,434
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	152,149	519,008
Quoted Prices in Active Markets for Identical Assets (Level 1) | Common stocks — mutual funds — equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	55,543	54,256
Quoted Prices in Active Markets for Identical Assets (Level 1) | Genuine Parts Company common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		176,640
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	76,937	72,749
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	374	1,422
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	18,878	12,365
Quoted Prices in Active Markets for Identical Assets (Level 1) | Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	416	329
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds-fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		201,247
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short Term Collective Trust
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Options and futures
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		0
Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	124,126	463,437
Significant Observable Inputs (Level 2) | Common stocks — mutual funds — equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Observable Inputs (Level 2) | Genuine Parts Company common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		0
Significant Observable Inputs (Level 2) | Other stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Observable Inputs (Level 2) | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Observable Inputs (Level 2) | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Observable Inputs (Level 2) | Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	51,946	52,052
Significant Observable Inputs (Level 2) | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	72,179	66,321
Significant Observable Inputs (Level 2) | Mutual funds-fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		0
Significant Observable Inputs (Level 2) | Short Term Collective Trust
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		345,064
Significant Observable Inputs (Level 2) | Options and futures
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		0
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	1,241,434
Significant Unobservable Inputs (Level 3) | Common stocks — mutual funds — equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Unobservable Inputs (Level 3) | Genuine Parts Company common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		0
Significant Unobservable Inputs (Level 3) | Other stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Unobservable Inputs (Level 3) | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Unobservable Inputs (Level 3) | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Unobservable Inputs (Level 3) | Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Significant Unobservable Inputs (Level 3) | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	$ 0	0
Significant Unobservable Inputs (Level 3) | Mutual funds-fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		0
Significant Unobservable Inputs (Level 3) | Short Term Collective Trust
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		0
Significant Unobservable Inputs (Level 3) | Options and futures
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets		$ 1,241,434