EQUITY COMPENSATION PLANS - Other Information (Details) - $ / shares	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
PBRSU Awards
Summary of PBRSU awards and restricted stock activity:
Stock awards outstanding, at the beginning of period (in shares)	1,362,836	1,386,687	1,444,189
Stock awards granted (in shares)	284,104	323,750	371,859
Stock awards vested/ earned (in shares)	(324,561)	(312,745)	(402,509)
Stock awards cancelled (in shares)	(55,026)	(34,856)	(26,852)
Stock awards outstanding, at the end of period (in shares)	1,267,353	1,362,836	1,386,687
Weighted-average fair value at grant-date of stock awards outstanding, at the beginning of period (in dollars per share)	$ 115.24	$ 107.70	$ 95.59
Weighted-average fair value at grant-date of stock awards granted (in dollars per share)	152.59	131.71	112.29
Weighted-average fair value at grant-date of stock awards vested/earned (in dollars per share)	103.15	99.65	68.64
Weighted-average fair value at grant-date of stock awards cancelled (in dollars per share)	114.25	108.16	105.09
Weighted-average fair value at grant-date of stock awards outstanding, at the end of period (in dollars per share)	$ 126.75	$ 115.24	$ 107.70
Restricted Stock Awards and Units
Summary of PBRSU awards and restricted stock activity:
Stock awards outstanding, at the beginning of period (in shares)	249,402	254,387	273,235
Stock awards granted (in shares)	109,074	96,980	88,437
Stock awards vested/ earned (in shares)	(92,032)	(86,622)	(96,874)
Stock awards cancelled (in shares)	(19,975)	(15,343)	(10,411)
Stock awards outstanding, at the end of period (in shares)	246,469	249,402	254,387
Weighted-average fair value at grant-date of stock awards outstanding, at the beginning of period (in dollars per share)	$ 116.66	$ 107.95	$ 102.49
Weighted-average fair value at grant-date of stock awards granted (in dollars per share)	138.69	125.34	109.27
Weighted-average fair value at grant-date of stock awards vested/earned (in dollars per share)	113.03	102.02	94.06
Weighted-average fair value at grant-date of stock awards cancelled (in dollars per share)	115.05	109.72	105.07
Weighted-average fair value at grant-date of stock awards outstanding, at the end of period (in dollars per share)	$ 127.09	$ 116.66	$ 107.95

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

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-SubTopic 10
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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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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