Common Stock, Capital Shares Reserved for Future Issuance, Amount of Annual Increase

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- Definition

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

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- Definition

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

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- Definition

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

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- Definition

Aggregate number of common shares reserved for future issuance.

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- Definition

Amount of cost capitalized for 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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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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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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- Definition

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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- Definition

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

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STOCKHOLDERS' EQUITY - Stock Plans and Share Based Compensation Narrative (Details) $ in Thousands		3 Months Ended		9 Months Ended
	Nov. 17, 2015 shares	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) plan shares	Sep. 30, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share based compensation plans \| plan				2
Employee stock purchase plan, compensation expense \| $		$ 77,426	$ 58,913	$ 217,980	$ 157,856
Capitalized share-based compensation expense \| $		2,400	2,000	6,000	6,300
Unrecognized compensation cost, options \| $		745,000		745,000
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock purchase plan, compensation expense \| $		$ 5,100	$ 2,000	$ 14,100	$ 6,300
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, period for recognition				2 years 9 months 18 days
2009 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)		0		0
2009 Stock Option Plan \| Stock options, RSAs, and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments outstanding (in shares)		20,422,313		20,422,313
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)		82,968,841		82,968,841
Shares reserved for future issuance (in shares)	30,000,000
Shares reserved for future issuance, percentage of annual increase	5.00%
2015 Equity Incentive Plan \| Stock options, RSAs, and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments outstanding (in shares)		21,822,262		21,822,262
2015 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance, amount of annual increase (in shares)	40,000,000