Business Segment Information - People's Republic of China Including Hong Kong Percentage Share of the Company's Total Revenue, Net Revenue, Total Identifiable Assets or Equity (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Total revenues | People's Republic of China, including Hong Kong
Concentration Risk [Line Items]
Concentration percentage	31.00%	32.00%	33.00%
Net revenues | People's Republic of China, including Hong Kong
Concentration Risk [Line Items]
Concentration percentage	18.00%	19.00%	16.00%
Identifiable assets at year end | People's Republic of China, including Hong Kong
Concentration Risk [Line Items]
Concentration percentage	15.00%	13.00%	14.00%
Equity | People's Republic of China, including Hong Kong
Concentration Risk [Line Items]
Concentration percentage	13.00%	10.00%	9.00%
Lower end | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration percentage	10.00%	10.00%	10.00%