Earnings Per Share - Summary of Anti-dilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential shares of common stock excluded from the computation of diluted earnings per share	1,682	898
Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential shares of common stock excluded from the computation of diluted earnings per share	69
RSUs & PSUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential shares of common stock excluded from the computation of diluted earnings per share	751	421
ESPP Purchase Rights [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential shares of common stock excluded from the computation of diluted earnings per share	862	477