Benefit Plans - Schedule of Weighted-Average Assumptions Used to Determine Fair Value of Option Granted (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (in years)	5 years	5 years	5 years
Expected volatility	28.70%	31.10%	40.50%
Expected dividend yields	4.10%	3.20%	3.00%
Risk-free interest rates	1.20%	1.60%	1.50%