Stock Option Activity (Detail)
shares in Thousands
6 Months Ended
Jun. 30, 2017
$ / shares
shares
Number of Shares  
Options outstanding, beginning of period | shares 3,292
Granted | shares 398
Canceled/Expired | shares (225)
Exercised | shares (79)
Options outstanding, end of period | shares 3,386
Weighted Average Exercise Price  
Options outstanding, beginning of period | $ / shares $ 32.06
Granted | $ / shares 32.55
Canceled/Expired | $ / shares 29.43
Exercised | $ / shares 20.88
Options outstanding, end of period | $ / shares $ 32.55