Benefit Plans - Schedule of Weighted-Average Assumptions Used to Determine Fair Value of Option Granted (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (in years)	5 years	5 years	5 years
Expected volatility	31.10%	40.50%	50.30%
Expected dividend yields	3.20%	3.00%	3.30%
Risk-free interest rates	1.60%	1.50%	0.80%