Stock Option Activity (Detail) (USD $)
In Thousands, except Per Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Number of Shares  
Options outstanding, beginning of period 2,649
Granted 363
Canceled/Expired (16)
Exercised (1)
Options outstanding, end of period 2,995
Weighted Average Exercise Price  
Options outstanding, beginning of period $ 32.33
Granted $ 42.80
Canceled/Expired $ 45.72
Exercised $ 25.43
Options outstanding, end of period $ 33.53