XML 99 R85.htm IDEA: XBRL DOCUMENT v3.3.1.900
Assumptions Used to Determine Weighted Average Grant Date Fair Value (Detail)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility 26.00% 32.00% 40.70%
Risk-free interest rates 1.80% 1.70% 0.80%
Derived service periods (in years) 1 month 6 days 3 months 18 days 1 month 6 days