Annual report pursuant to Section 13 and 15(d)

Stock Option and Purchase Plans - Summary of Company's Stock Option Activity and Related Information (Detail)

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Stock Option and Purchase Plans - Summary of Company's Stock Option Activity and Related Information (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]      
Option Outstanding, Beginning balance 1,521,275 1,661,445 1,904,232
Options Granted 69,720 130,500 84,938
Options Exercised (181,218) (270,670) (327,725)
Options Forfeited         
Option Outstanding, Ending balance 1,409,777 1,521,275 1,661,445
Option Exercisable, Ending balance 1,149,532 1,168,459 1,280,744
Weighted Average Exercise Price, Outstanding, Beginning balance $ 8.23 $ 6.71 $ 5.58
Weighted Average Exercise Price, Options Granted $ 42.67 $ 18.08 $ 22.44
Weighted Average Exercise Price, Options Exercised $ 4.25 $ 3.67 $ 4.25
Weighted Average Exercise Price, Options Forfeited         
Weighted Average Exercise Price, Outstanding, Ending balance $ 10.44 $ 8.23 $ 6.71
Weighted Average Exercise Price, Exercisable , Ending balance $ 7.81 $ 6.72 $ 5.47
Aggregate Intrinsic Value, Outstanding , Beginning Balance $ 65,072 $ 20,532 $ 38,778
Aggregate Intrinsic Value, Options Granted 581 129 299
Aggregate Intrinsic Value, Options Exercised (8,472) (4,168) (7,112)
Aggregate Intrinsic Value, Options Forfeited         
Aggregate Intrinsic Value, Outstanding, Ending Balance 57,181 16,493 31,965
Aggregate Intrinsic Value, Exercisable , Ending balance $ 49,648 $ 14,431 $ 26,237