EQUITY COMPENSATION PLANS - Other Information (Details) - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
PBRSU Awards
Summary of PBRSU awards and restricted stock activity:
Stock awards outstanding, at the beginning of period (in shares)	1,267,353	1,362,836	1,386,687
Stock awards granted (in shares)	207,704	284,104	323,750
Stock awards vested/ earned (in shares)	(334,351)	(324,561)	(312,745)
Stock awards cancelled (in shares)	(23,808)	(55,026)	(34,856)
Stock awards outstanding, at the end of period (in shares)	1,116,898	1,267,353	1,362,836
Weighted-average fair value at grant-date of stock awards outstanding, at the beginning of period (in dollars per share)	$ 126.75	$ 115.24	$ 107.70
Weighted-average fair value at grant-date of stock awards granted (in dollars per share)	178.20	152.59	131.71
Weighted-average fair value at grant-date of stock awards vested/earned (in dollars per share)	114.38	103.15	99.65
Weighted-average fair value at grant-date of stock awards cancelled (in dollars per share)	135.70	114.25	108.16
Weighted-average fair value at grant-date of stock awards outstanding, at the end of period (in dollars per share)	$ 139.83	$ 126.75	$ 115.24
Restricted Stock Awards and Units
Summary of PBRSU awards and restricted stock activity:
Stock awards outstanding, at the beginning of period (in shares)	246,469	249,402	254,387
Stock awards granted (in shares)	102,941	109,074	96,980
Stock awards vested/ earned (in shares)	(64,597)	(92,032)	(86,622)
Stock awards cancelled (in shares)	(19,300)	(19,975)	(15,343)
Stock awards outstanding, at the end of period (in shares)	265,513	246,469	249,402
Weighted-average fair value at grant-date of stock awards outstanding, at the beginning of period (in dollars per share)	$ 127.09	$ 116.66	$ 107.95
Weighted-average fair value at grant-date of stock awards granted (in dollars per share)	177.38	138.69	125.34
Weighted-average fair value at grant-date of stock awards vested/earned (in dollars per share)	119.08	113.03	102.02
Weighted-average fair value at grant-date of stock awards cancelled (in dollars per share)	124.77	115.05	109.72
Weighted-average fair value at grant-date of stock awards outstanding, at the end of period (in dollars per share)	$ 149.46	$ 127.09	$ 116.66

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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