Employee Benefit Plans - Fair Value of Plan Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	$ 1,933,063,000	$ 1,595,679,000
Common Stocks - Mutual Funds - Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	505,572,000	342,846,000
Other Stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	791,728,000	608,017,000
Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	59,058,000	37,626,000
Cash and Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	9,022,000	45,719,000
Government Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	144,447,000	166,413,000
Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	123,773,000	127,824,000
Asset-Backed and Mortgage-Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	19,345,000	24,077,000
Other-International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	12,072,000	10,188,000
Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1,304,000	532,000
Municipal Funds-Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	96,231,000	101,578,000
Cash Surrender Value of Life Insurance Policies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	2,723,000	2,623,000
Genuine Parts Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	167,788,000	128,236,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1,605,539,000	1,247,339,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common Stocks - Mutual Funds - Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	505,572,000	342,846,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	791,728,000	608,017,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	59,058,000	37,626,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash and Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	9,022,000	45,719,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Government Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	61,171,000	74,707,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Asset-Backed and Mortgage-Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other-International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	11,200,000	10,188,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal Funds-Fixed Income [Member]
Defined Benefit Plan Disclosure [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]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Genuine Parts Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	167,788,000	128,236,000
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	324,801,000	345,717,000
Significant Observable Inputs (Level 2) [Member] | Common Stocks - Mutual Funds - Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Other Stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Cash and Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Government Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	83,276,000	91,706,000
Significant Observable Inputs (Level 2) [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	123,773,000	127,824,000
Significant Observable Inputs (Level 2) [Member] | Asset-Backed and Mortgage-Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	19,345,000	24,077,000
Significant Observable Inputs (Level 2) [Member] | Other-International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	872,000
Significant Observable Inputs (Level 2) [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1,304,000	532,000
Significant Observable Inputs (Level 2) [Member] | Municipal Funds-Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	96,231,000	101,578,000
Significant Observable Inputs (Level 2) [Member] | Cash Surrender Value of Life Insurance Policies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Observable Inputs (Level 2) [Member] | Genuine Parts Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	2,723,000	2,623,000
Significant Unobservable Inputs (Level 3) [Member] | Common Stocks - Mutual Funds - Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Other Stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Cash and Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Government Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Asset-Backed and Mortgage-Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Other-International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Municipal Funds-Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets
Significant Unobservable Inputs (Level 3) [Member] | Cash Surrender Value of Life Insurance Policies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	2,723,000	2,623,000
Significant Unobservable Inputs (Level 3) [Member] | Genuine Parts Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets