Weighted Average Assumptions used in Black Scholes Option Valuation Model (Parenthetical) (Detail) - $ / shares		12 Months Ended
	May 27, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected annual dividend rate per share		$ 0.12
Expected quarterly dividend rate per share		0.03
Cash dividends declared, per share	$ 0.030	0.12	$ 0.12	$ 0.105
Post-Split Basis
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected annual dividend rate per share		0.06
Expected quarterly dividend rate per share		$ 0.015
Cash dividends declared, per share	$ 0.015