SHARE-BASED COMPENSATION - Schedule Of Estimated Fair Value Of Option Using Black-Scholes Option Pricing Model, Weighted Average Assumptions (Details) - $ / shares	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.60%	2.00%
Expected term (in years)	4 years 3 months 18 days	4 years 4 months 1 day
Expected volatility (percent)	33.00%	25.00%
Weighted average fair value at grant date (usd per share)	$ 130.51	$ 56.52
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.90%	0.90%
Expected term (in years)	1 year 2 months 12 days	1 year 4 months 1 day
Expected volatility (percent)	32.00%	26.00%
Weighted average fair value at grant date (usd per share)	$ 124.61	$ 61.59

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Weighted average expected volatility rate of share-based compensation awards.

+ References

+ Details

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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.

+ References

No definition available.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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+ Details

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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