Employee Benefit Plans (Other Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined contribution plan contribution rates as percentage of employee earnings	6.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100.00%
Compensation expense related to the ESOP	$ 49	$ 47	$ 46
Deductible dividends on PPG shares held by the ESOP	11	13	14
Recognized expense for defined contribution pension plans	70	63	57
Expense (income) of the deferred compensation plan	21	(1)	19
Increase (Decrease) in fair value of investments	20	(2)	$ 18
Obligations under the deferred compensation plan	123	110
Investments in marketable securities by the deferred compensation plan	$ 85	$ 73