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Common Stock - Summary of Information and Changes in Stock Options with Regard to Stock Option Plans (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]      
Number of shares under stock option, Beginning of the year 21,009,508 22,472,047 17,439,060
Number of Shares Granted 1,493,576 1,610,599 6,961,041
Number of Shares Forfeited (944,917) (1,318,380) (1,482,531)
Number of Shares Exercised (248,068) (1,754,758) (445,523)
Number of shares under stock option, End of the year 21,310,099 21,009,508 22,472,047
Number of stock options, Exercisable 17,796,607 15,223,029 14,309,944
Weighted Average Exercise Price, Beginning of year $ 48.88 $ 48.99 $ 54.08
Weighted Average Exercise Price, Stock Options Granted 28.72 35.09 36.51
Weighted Average Exercise Price, Stock Options Forfeited 50.57 57.56 55.22
Weighted Average Exercise Price, Stock Options Exercised 29.70 44.12 29.83
Weighted Average Exercise Price, End of the year 47.68 48.88 48.99
Weighted Average Exercise Price, Stock Options, Exercisable $ 50.49 $ 54.13 $ 55.00
Weighted Average Remaining Contractual Term, Outstanding 5 years 4 months 9 days   6 years 3 days
Weighted Average Remaining Contractual Term, Exercisable 4 years 5 months 8 days    
Stock Options Aggregate Intrinsic Value, Beginning $ 458,576    
Stock Options Aggregate Intrinsic Value, Ending   $ 458,576