STOCK INCENTIVE PLANS - Performance Shares and Restricted Stock Units (Details) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Outstanding at beginning of period (in shares) \| shares	73,160	57,236	57,533
Issued (in shares) \| shares	60,414	47,264	32,194
Canceled (in shares) \| shares	(11,724)	(13,108)	(6,835)
Vested (in shares) \| shares	(23,510)	(18,232)	(25,656)
Outstanding at end of period (in shares) \| shares	98,340	73,160	57,236
Weighted Average Price Per Share [Abstract]
Outstanding at beginning of period, weighted average price per share (in dollars per share) \| $ / shares	$ 232.72	$ 220.00	$ 185.02
Issued, weighted average price per share (in dollars per share) \| $ / shares	191.38	227.26	242.65
Cancelled, weighted average price per share (in dollars per share) \| $ / shares	241.41	215.01	190.90
Vested, weighted average price per share (in dollars per share) \| $ / shares	242.65	191.36	177.75
Outstanding at end of period, weighted average price per share (in dollars per share) \| $ / shares	$ 203.91	$ 232.72	$ 220.00
Unearned unrecognized compensation \| $	$ 11,500
Weighted average period to recognize (in years)	3 years 2 months 12 days
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion ratio	1
Fair value of shares vested \| $	$ 21,367	$ 25,865	$ 28,650
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Outstanding at beginning of period (in shares) \| shares	432,783	560,351	739,717
Issued (in shares) \| shares	113,909	104,220	103,427
Canceled (in shares) \| shares	(62,869)	(38,124)	(51,410)
Vested (in shares) \| shares	(110,420)	(193,664)	(231,383)
Outstanding at end of period (in shares) \| shares	373,403	432,783	560,351
Weighted Average Price Per Share [Abstract]
Outstanding at beginning of period, weighted average price per share (in dollars per share) \| $ / shares	$ 213.45	$ 182.40	$ 154.09
Issued, weighted average price per share (in dollars per share) \| $ / shares	230.36	234.21	248.12
Cancelled, weighted average price per share (in dollars per share) \| $ / shares	229.70	219.74	170.98
Vested, weighted average price per share (in dollars per share) \| $ / shares	193.51	133.56	123.82
Outstanding at end of period, weighted average price per share (in dollars per share) \| $ / shares	$ 221.77	$ 213.45	$ 182.40
Unearned unrecognized compensation \| $	$ 43,000
Weighted average period to recognize (in years)	3 years
Minimum [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Minimum [Member] \| Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Maximum [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	7 years
Maximum [Member] \| Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	7 years

Share-Based Compensation Arrangement By Share-Based Payment Award, Conversion Ratio

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Share-Based Compensation Fair Value of Vested Restricted Stock Units

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
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- Definition

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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
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- Definition

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).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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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No definition available.

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- Definition

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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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- Definition

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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