Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Components of Provision for Income Taxes

The provision for (benefit from) income taxes consists of the following (in thousands):

	Year Ended December 31,
	2018			2017			2016
				*As Adjusted			*As Adjusted
Current provision:
Federal	$	(336	)	$	(445	)	$	(55	)
State	163			137			135
Foreign	22,204			9,512			5,098
	22,031			9,204			5,178
Deferred provision:
Federal	(2,026		)	(5,934		)	(4,462		)
State	(377		)	(886		)	(746		)
Foreign	(31,948		)	1,056			3,860
	(34,351		)	(5,764		)	(1,348		)
Provision for (benefit from) income taxes	$	(12,320	)	$	3,440		$	3,830

*As adjusted to reflect the impact of the full retrospective adoption of Topic 606. See Note 2 for further details.

Components of Loss From Continuing Operations Before Income Taxes

The components of loss before provision for income taxes by U.S. and foreign jurisdictions were as follows (in thousands):

	Year Ended December 31,
	2018			2017			2016
				*As Adjusted			*As Adjusted
United States	(153,290		)	(61,259		)	(403,161		)
Foreign	114,266			(52,147		)	(7,258		)
Total	$	(39,024	)	$	(113,406	)	$	(410,419	)

*As adjusted to reflect the impact of the full retrospective adoption of Topic 606. See Note 2 for further details.

Reconciliation of Federal Income Tax Rate

The effective income tax rate differs from the federal statutory income tax rate applied to the loss before provision for income taxes due to the following (in thousands): 

	Year Ended December 31,
	2018			2017			2016
				*As Adjusted			*As Adjusted
Tax computed at U.S. federal statutory rate	$	(8,195	)	$	(38,558	)	$	(139,542	)
State taxes, net of federal benefit	98			64			37
Tax rate differential for international subsidiaries	(41,429		)	23,532			8,020
Stock-based compensation	(93,073		)	(116,953		)	(27,133		)
Tax credits	(44,695		)	(21,038		)	(16,452		)
Foreign restructuring and amortization	(625,292		)	2,794			3,169
Non-deductible expenses	9,657			2,833			1,892
Tax effects associated with Topic 606	(23,073		)	3,314			2,076
Other	408			607			896
Valuation allowance	813,274			146,845			170,867
Provision for income taxes	$	(12,320	)	$	3,440		$	3,830

*As adjusted to reflect the impact of the full retrospective adoption of Topic 606. See Note 2 for further details.

Reconciliation of Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets are shown below (in thousands). A valuation allowance has been recognized to offset our deferred tax assets, as necessary, by the amount of any tax benefits that, based on evidence, are not expected to be realized.

	December 31,
	2018			2017
				*As Adjusted
Deferred tax assets:
Net operating loss carryforwards	$	610,314		$	518,620
Accrued expenses	13,482			10,613
Credit carryforwards	120,594			75,879
Stock-based compensation	44,510			35,782
Note hedge	22,742			35,181
Depreciation and amortization	593,348			—
Other	23,183			14,771
Total deferred tax assets	1,428,173			690,846
Less valuation allowance	(1,337,350		)	(583,235		)
	90,823			107,611
Deferred tax liabilities:
Depreciation and amortization	(22,183		)	(20,708		)
Convertible notes	(24,887		)	(43,616		)
Tax effects associated with Topic 606	(23,531		)	(53,601		)
Other	(1,568		)	(1,759		)
Net deferred tax assets	$	18,654		$	(12,073	)

*As adjusted to reflect the impact of the full retrospective adoption of Topic 606. See Note 2 for further details.

Reconciliation of Beginning and Ending Balance of Total Unrecognized Tax Benefits

A reconciliation of the beginning and ending balance of total unrecognized tax benefits is as follows (in thousands):

	Year Ended December 31,
	2018			2017		2016
Balance, beginning period	$	27,648		$	18,440	$	11,737
Tax positions taken in prior period:
Gross increases	3,721			398		1,122
Gross decreases	(2,896		)	—		(50		)
Tax positions taken in current period:
Gross increases	5,796			8,810		5,673
Gross decreases	—			—		—
Lapse of statute of limitations	(1,078		)	—		(42		)
Settlements	(5,600		)	—		—
Balance, end of period	$	27,591		$	27,648	$	18,440