Quarterly Financial Data (Unaudited) - Summary of Unaudited Quarterly Results (Parenthetical) (Detail) - ASU 2016-09 [Member] - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Quarterly Financial Data [Line Items]
Adjustments to net income	$ 0.1	$ 0.1	$ 0.1	$ 0.1
Adjusted basic net income per share				$ 0.20
Adjusted diluted net income per share				0.20
Previously Reported [Member]
Quarterly Financial Data [Line Items]
Adjusted basic net income per share				0.19
Adjusted diluted net income per share				$ 0.19