Quarterly Results (Unaudited) (Parenthetical) (Detail) - People's Republic of China, including Hong Kong - Geographic Concentration Risk	3 Months Ended	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Revenues:
Concentration percentage	25.00%	31.00%	26.00%	29.00%	31.00%
Operating Income
Revenues:
Concentration percentage	25.00%	27.00%	27.00%	30.00%	30.00%

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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