Significant Accounting Policies - Summary of Assumptions for Options Granted (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Volatility factor	23.60%	30.90%	38.50%
Dividend yield	0.90%	0.90%	1.10%
Expected term (in years)	5 years 7 months 28 days	5 years 7 months 24 days	5 years 7 months 13 days
Risk-free rate	1.60%	1.90%	1.10%