Commitments and Contingencies - Approximate Percentage of TiO2 Sales by Volume for Segments (Detail) - TiO2 - Geographic Concentration Risk - Net Sales - Chemicals	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Europe
Schedule Of Sales Revenue By Business Segment [Line Items]
Concentration risk percentage	46.00%	46.00%	44.00%
North America
Schedule Of Sales Revenue By Business Segment [Line Items]
Concentration risk percentage	36.00%	34.00%	37.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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