Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Income before Income Taxes

The geographical breakdown of income before provision for income taxes is as follows (in thousands):

	Year Ended December 31,
	2017		2016		2015
Domestic	$	373,221	$	196,202	$	129,240
Foreign	101,539		46,023		16,769
Income before provision for income taxes	$	474,760	$	242,225	$	146,009

Schedule of Components of Income Tax Expense (Benefit)

The components of the provision for income taxes are as follows (in thousands):

	Year Ended December 31,
	2017			2016			2015
Current provision for income taxes:
Federal	$	36,862		$	67,253		$	43,706
State	3,645			10,529			5,500
Foreign	2,395			2,016			1,588
Total current	42,902			79,798			50,794
Deferred taxes:
Federal	12,795			(18,579		)	(23,896		)
State	(3,404		)	(3,564		)	(2,300		)
Foreign	(734		)	381			309
Total deferred	8,657			(21,762		)	(25,887		)
Total provision for income taxes	$	51,559		$	58,036		$	24,907

Schedule of Effective Income Tax Rate Reconciliation

The reconciliation of the statutory federal income tax and our effective income tax is as follows:

	Year Ended December 31,
	2017		2016		2015
U.S. federal statutory income tax	35.00	%	35.00	%	35.00	%
State tax, net of federal benefit	(1.70	)	(0.03	)	(1.35	)
Foreign tax differential	(7.62	)	(3.24	)	(2.16	)
Tax credits	(3.84	)	(4.24	)	(6.72	)
Change in valuation allowance	1.95		1.71		2.84
Permanent items	(1.10	)	(1.02	)	(1.32	)
Uncertain tax positions and associated interest	0.77		(1.46	)	(3.95	)
Stock-based compensation	(23.74	)	(2.81	)	(5.29	)
Tax Cuts and Jobs Act	11.14		—		—
Other, net	—		0.05		0.01
Total provision for income taxes	10.86	%	23.96	%	17.06	%

Schedule of Deferred Tax Assets and Liabilities

The tax effects of temporary differences that give rise to significant portions of deferred tax assets (liabilities) are as follows (in thousands):

	December 31,
	2017			2016
Deferred tax assets:
Property and equipment	$	1,942		$	473
Stock-based compensation	22,050			23,071
Reserves and accruals not currently deductible	41,024			49,436
Net operating losses	2,432			1,140
Tax credits	30,831			15,015
Other	2,115			194
Gross deferred tax assets	100,394			89,329
Valuation allowance	(35,132		)	(16,894		)
Total deferred tax assets	65,262			72,435
Deferred tax liabilities:
Property and equipment	—			(198		)
Accrued liabilities	(2,006		)	(2,555		)
Other	(9		)	(3		)
Total deferred tax liabilities	(2,015		)	(2,756		)
Net deferred tax assets	$	63,247		$	69,679

The following table presents the breakdown between non-current deferred tax assets and liabilities (in thousands):

	December 31,
	2017			2016
Deferred tax assets, non-current	$	65,125		$	70,960
Deferred tax liabilities, non-current	(1,878		)	(1,281		)
Total net deferred tax assets	$	63,247			$69,679

Schedule of Unrecognized Tax Benefits Roll Forward

The reconciliation of the beginning and ending amount of gross unrecognized tax benefits as of December 31, 2017, 2016 and 2015 was as follows (in thousands):

	Year Ended December 31,
	2017			2016			2015
Gross unrecognized tax benefits—beginning balance	$	26,915		$	22,239		$	21,322
Increases related to tax positions taken in a prior year	1,243			46			346
Increases related to tax positions taken during current year	22,202			11,359			7,385
Decreases related to tax positions taken in a prior year	(21		)	(426		)	(228		)
Decreases related to settlements with taxing authorities	—			(432		)	—
Decreases related to lapse of statute of limitations	(1,504		)	(5,871		)	(6,586		)
Gross unrecognized tax benefits—ending balance	$	48,835		$	26,915		$	22,239