INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Domestic and Foreign Components of Loss Before Income Taxes

The domestic and foreign components of loss before income taxes are as follows (in thousands):

	Year Ended December 31,
	2017			2016			2015
Domestic	$	(10,900	)	$	(145,499	)	$	(157,229	)
Foreign	(51,764		)	(24,174		)	(18,842		)
Loss before income taxes	$	(62,664	)	$	(169,673	)	$	(176,071	)

Components of Provision for Income Taxes

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

	Year Ended December 31,
	2017			2016			2015
Current:
Federal	$	(1,192	)	$	63		$	1,662
State	739			527			836
Foreign	1,987			1,269			1,222
Total current provision for income taxes	1,534			1,859			3,720
Deferred:
Federal	(1,169		)	173			67
State	57			18			11
Foreign	(273		)	(133		)	(52		)
Total deferred provision for income taxes	(1,385		)	58			26
Total provision for income taxes	$	149		$	1,917		$	3,746

Reconciliation of Statutory Federal Income Tax Rate to Company's Effective Tax Rate

The following is a reconciliation of the statutory federal income tax rate to the Company's effective tax rate:

	Balance at December 31,
	2017		2016		2015
Tax at federal statutory rate	34.0	%	34.0	%	34.0	%
State taxes, net of federal benefit	(0.4	)	(0.1	)	(0.2	)
Foreign rate differential	(14.9	)	(2.4	)	(1.8	)
Nondeductible expenses	(1.0	)	(0.9	)	(1.1	)
Credits	41.5		8.5		8.2
Other items	(1.2	)	0.2		0.1
Change in valuation allowance	(119.5	)	(37.4	)	(38.6	)
Impact of U.S. tax reform	(209.1	)	—		—
Share-based compensation (i)	243.5		(2.4	)	(2.2	)
Change in uncertain tax positions	(2.4	)	(0.6	)	(0.5	)
Termination of warrant	29.3		—		—
Total	(0.2	)%	(1.1	)%	(2.1	)%

⁽ⁱ⁾ Starting in 2017, excess tax benefits from share-based award activity are reflected in the provision for income taxes.

Tax Effects of Temporary Differences and Related Deferred Tax Assets and Liabilities

The tax effects of temporary differences and related deferred tax assets and liabilities are as follows (in thousands):

	Balance at December 31,
	2017			2016			2015
Deferred tax assets:
Capitalized costs	$	35,608		$	61,897		$	67,051
Accrued expenses	23,553			29,421			27,964
Net operating loss carryforwards	244,197			65,507			36,633
Tax credit carryforwards	60,567			38,927			25,349
Property, equipment and intangible assets	7,390			5,721			—
Share-based compensation	35,728			52,091			36,689
Other	2,519			1,640			1,469
Total deferred tax assets	409,562			255,204			195,155
Valuation allowance	(409,043		)	(254,898		)	(195,103		)
Total deferred tax assets, net of valuation allowance	519			306			52
Deferred tax liabilities:
Property, equipment and intangible assets	(644		)	(476		)	(163		)
Total deferred tax liabilities	(644		)	(476		)	(163		)
Net deferred tax liabilities	$	(125	)	$	(170	)	$	(111	)

Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefit

A reconciliation of the beginning and ending amount of unrecognized tax benefit is presented below (in thousands):

	Year Ended December 31,
	2017			2016			2015
Balance at the beginning of the year	$	92,134		$	90,372		$	78,031
Gross increases and decreases related to prior period tax positions	—			5,190			—
Gross increases and decreases related to current period tax positions	4,193			(3,428		)	12,341
Reductions related to lapse of statute of limitations	(91		)	—			—
Gross increases and decreases related to U.S. tax reform	(25,437		)	—			—
Balance at the end of the year	$	70,799		$	92,134		$	90,372