Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation - Stock Options Outstanding (Detail)

v3.10.0.1
Stock Based Compensation - Stock Options Outstanding (Detail)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2018
USD ($)
$ / shares
shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Outstanding, Options | shares 23,000
Outstanding, Weighted average exercise price $ 78.87
Exercisable, Options | shares 23,000
Exercisable, Weighted average exercise price $ 78.87
Intrinsic value of outstanding stock options at December 31, 2018 | $ $ 324,840
Intrinsic value of exercisable stock options at December 31, 2018 | $ $ 324,840
$49.42 - 69.99 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, minimum $ 49.42
Exercise Price Range, maximum $ 69.99
Outstanding, Options | shares 5,500
Outstanding, Weighted average exercise price $ 56.87
Exercisable, Options | shares 5,500
Exercisable, Weighted average exercise price $ 56.87
$70.00 - 91.58 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, minimum 70.00
Exercise Price Range, maximum $ 91.58
Outstanding, Options | shares 17,500
Outstanding, Weighted average exercise price $ 85.78
Exercisable, Options | shares 17,500
Exercisable, Weighted average exercise price $ 85.78