Amortization period of defined benefit plan assets gain loss.

No definition available.

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- Definition

Defined benefit plan assumptions used calculating net periodic benefit cost expected long term return on assets for next fiscal year.

+ References

No definition available.

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- Definition

Defined benefit plan percentage of employer and related party securities included in plan assets.

+ References

No definition available.

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- Definition

Defined Contribution Plan, Number of Plans

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No definition available.

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- Definition

Passive portfolio benchmark.

+ References

No definition available.

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- Definition

Pension benefits expected to be paid from employer assets.

+ References

No definition available.

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- Definition

Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

+ References

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- Definition

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

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- Definition

Amount of increase in benefit obligation for benefits provided to employees payable from defined benefit plan or payable upon retirement.

+ References

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- Definition

Amount of cost for defined contribution plan.

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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

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Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

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- Definition

Amount of dividend income on nonoperating securities.

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Employee Benefit Plans - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) plan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Amortization period of plan assets gains and losses (in years)	5 years
Benefit obligations	$ 2,496,600	$ 2,278,043	$ 2,435,765
Total accumulated benefit obligations	2,466,322	2,247,013
Special termination costs	42,757	0
Fair value of plan assets	$ 2,311,227	$ 2,043,379	2,206,479
Genuine Parts Company common stock as a percentage of total plan assets	9.00%	9.00%
Dividend payments on Genuine Parts Company common stock received by plan	$ 6,156	$ 5,813
Expected rate of return on plan assets for measuring next fiscal year pension cost or income	7.11%
Pension benefits expected to be paid from employer assets in next fiscal year	$ 11,694
S&P 500 Index
Defined Benefit Plan Disclosure [Line Items]
Passive portfolio benchmark	47.00%
Russell Mid Cap Index
Defined Benefit Plan Disclosure [Line Items]
Passive portfolio benchmark	5.00%
Russell 2000 Index
Defined Benefit Plan Disclosure [Line Items]
Passive portfolio benchmark	7.00%
MSCI EAFE Index
Defined Benefit Plan Disclosure [Line Items]
Passive portfolio benchmark	5.00%
DJ Global Moderate Index
Defined Benefit Plan Disclosure [Line Items]
Passive portfolio benchmark	5.00%
MSCI Emerging Market Net
Defined Benefit Plan Disclosure [Line Items]
Passive portfolio benchmark	3.00%
BarCap U.S. Govt/Credit
Defined Benefit Plan Disclosure [Line Items]
Passive portfolio benchmark	28.00%
Genuine Parts Company common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 214,418	193,810
United States
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations	2,228,066	2,055,701
Fair value of plan assets	$ 2,051,474	1,831,513
Number of plans \| plan	1
Matching contribution to be received by pension plan participants of a specified percentage of employee's salary	100.00%
First percentage of employee's salary out of which matching contribution will be made	5.00%
Total defined contribution plans expense	$ 64,990	62,335	$ 58,186
Canada
Defined Benefit Plan Disclosure [Line Items]
Matching contribution to be received by pension plan participants of a specified percentage of employee's salary	100.00%
First percentage of employee's salary out of which matching contribution will be made	5.00%
Total defined contribution plans expense	$ 4,433	$ 4,108