XML 52 R41.htm IDEA: XBRL DOCUMENT v3.7.0.1
Earnings Per Share - Summary of Earnings Per Share (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Numerator (in millions):    
Net income available to common stockholders $ 17.2 $ 18.9
Denominator (in thousands):    
Weighted average common shares outstanding 24,087 24,019
Dilutive effect of stock options and awards 440 464
Denominator for diluted earnings per share 24,527 24,483
Net income per share, basic: $ 0.71 $ 0.79
Net income per share, diluted: $ 0.70 $ 0.77