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Share-Based Compensation Arrangement by Share-based Payment Award, Discount as a Percent of Eligible Compensation

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Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments, Outstanding, Number

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Share-based Compensation Arrangement by Share-based Payment Award, Number of Payment Periods

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Share-based Compensation Arrangement by Share-based Payment Award, Number of Share Based Compensation Plans

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Share-based Compensation Arrangement by Share-based Payment Award, Offering Period

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Aggregate number of common shares reserved for future issuance.

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Amount of cost capitalized for award under share-based payment arrangement.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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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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Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

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Number of shares issued under share-based payment arrangement.

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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Purchase price of common stock expressed as a percentage of its fair value.

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STOCKHOLDER'S EQUITY - Stock Plans, Narrative (Details) $ / shares in Units, $ in Thousands			12 Months Ended			49 Months Ended
	Nov. 02, 2019	Nov. 17, 2015 payment_plan shares	Dec. 31, 2019 USD ($) plan $ / shares shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2019 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans \| plan			2
Aggregate intrinsic value for options exercised \| $			$ 616,300	$ 720,100	$ 464,100
Weighted average grant-date fair value of options granted (in USD per share) \| $ / shares			$ 30.58	$ 16.25	$ 5.97
Share-based compensation expense \| $			$ 297,863	$ 216,881	$ 155,836
Share-based compensation expense related to capitalized software \| $			8,200	9,300	3,700
Unrecognized compensation cost related to outstanding stock options and restricted stock awards \| $			$ 687,300			$ 687,300
Unrecognized compensation cost related to outstanding stock options and restricted stock awards, recognition period			2 years 8 months 23 days
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense \| $			$ 18,900	$ 9,000	$ 6,000
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance (in shares)			84,133,011			84,133,011
Number of shares reserved (in shares)		30,000,000
Shares reserved for issuance, percent			5.00%
2015 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase of number of shares reserved (in shares)			40,000,000			40,000,000
2015 Equity Incentive Plan \| Options and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options and RSU outstanding (in shares)			19,340,627			19,340,627
2009 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance (in shares)			0			0
2009 Stock Option Plan \| Options and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options and RSU outstanding (in shares)			18,196,638			18,196,638
2009 Stock Option Plan \| Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term			4 years
Expiration period			10 years
2009 Stock Option Plan \| Options \| Vesting Year One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting rate			25.00%
2015 Employee Stock Purchase Plan \| Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance (in shares)			14,294,425			14,294,425
Shares reserved for issuance, percent		1.00%
Discount through payroll deductions as a percentage of eligible compensation	25.00%	15.00%
Offering period		12 months
Number of purchase periods \| payment_plan		2
Purchase price of common stock as a percentage of fair market value		85.00%
Shares purchased under the plan (in shares)						5,022,962
2015 Employee Stock Purchase Plan \| Employee Stock Purchase Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase of number of shares reserved (in shares)		8,400,000