STOCK-BASED COMPENSATION (Summary of Option Activity) (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Stock Awards Plans
Stock options activity
Outstanding at the beginning of the period (in shares)	5,044,180
Granted (in shares)	0
Exercised (in shares)	(785,478)
Forfeited or expired (in shares)	(14,200)
Outstanding at the end of the period (in shares)	4,244,502
Stock option weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 68.32
Options granted, Weighted average exercise price per share (in dollars per share)	0
Options exercised, Weighted average exercise price per share (in dollars per share)	59.98
Options forfeited or expired, Weighted average exercise price per share (in dollars per share)	76.07
Outstanding at the end of the period (in dollars per share)	$ 69.91
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options exercisable, Number of options (in shares)	4,089,846
Options exercisable, Weighted average exercise price per share (in dollars per share)	$ 69.11
Options outstanding, Weighted average remaining contractual term (in years)	4 years 10 months 24 days
Options exercisable, Weighted average remaining contractual term (in years)	4 years 9 months 18 days
Options outstanding, Aggregate intrinsic value (in USD)	$ 183,753
Options exercisable, Aggregate intrinsic value (in USD)	179,771
Options exercised, Intrinsic value, during the nine months ended	$ 44,086	$ 76,797
Director Stock Option Plans
Stock options activity
Outstanding at the beginning of the period (in shares)	135,251
Granted (in shares)	0
Exercised (in shares)	(34,151)
Forfeited or expired (in shares)	0
Outstanding at the end of the period (in shares)	101,100
Stock option weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 58.45
Options granted, Weighted average exercise price per share (in dollars per share)	0
Options exercised, Weighted average exercise price per share (in dollars per share)	51.75
Options forfeited or expired, Weighted average exercise price per share (in dollars per share)	0
Outstanding at the end of the period (in dollars per share)	$ 60.71
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options exercisable, Number of options (in shares)	101,100
Options exercisable, Weighted average exercise price per share (in dollars per share)	$ 60.71
Options outstanding, Weighted average remaining contractual term (in years)	2 years 10 months 24 days
Options exercisable, Weighted average remaining contractual term (in years)	2 years 10 months 24 days
Options outstanding, Aggregate intrinsic value (in USD)	$ 5,306
Options exercisable, Aggregate intrinsic value (in USD)	5,306
Options exercised, Intrinsic value, during the nine months ended	$ 2,183	$ 722

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Number of options outstanding, including both vested and non-vested options.

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