Business Segment Information - People's Republic of China, including Hong Kong - Geographic Concentration Risk (Detail) - Peoples Republic Of China Including Hong Kong - Geographic Concentration Risk	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues
Concentration Risk [Line Items]
Concentration percentage	34.00%	25.00%	32.00%	26.00%	29.00%
Operating Income
Concentration Risk [Line Items]
Concentration percentage	27.00%	25.00%	29.00%	27.00%	30.00%
Identifiable assets at year end
Concentration Risk [Line Items]
Concentration percentage			14.00%	12.00%	14.00%
Equity
Concentration Risk [Line Items]
Concentration percentage			6.00%	9.00%	8.00%