Restructuring charges

Restructuring charges for each period were as follows:



	Year ended December 31,
(in thousands)	2018		2017		2016
Cost of revenue	$	1,379	$	634	$	497
Research and development	12,794		10,092		17,197
Sales and marketing	5,291		7,047		12,064
General and administrative	3,279		2,519		13,331
Total restructuring charges	$	22,743	$	20,292	$	43,089

First quarter 2018 restructuring plan

On January 2, 2018, the Company approved a restructuring plan to further reduce future operating expenses and better align resources around its long-term business strategy. The restructuring provided for a reduction of the Company's global workforce of approximately 18%, the closure of the Company's aerial group and the consolidation of certain leased office facilities. Under the first quarter 2018 restructuring plan, the Company recorded restructuring charges of $17.8 million, including $14.1 million related to severance and $3.7 million related to other charges.

The following table provides a summary of the Company’s restructuring activities and the related liabilities recorded in accrued liabilities on the consolidated balance sheet under the first quarter 2018 restructuring plan.



(in thousands)	Severance			Other			Total
Restructuring liability as of December 31, 2017	$	—		$	—		$	—
Restructuring charges	14,107			3,686			17,793
Cash paid	(12,460		)	(1,988		)	(14,448		)
Non-cash reductions	(528		)	(1,299		)	(1,827		)
Restructuring liability as of December 31, 2018	$	1,119		$	399		$	1,518

First quarter 2017 restructuring plan

On March 15, 2017, the Company approved a restructuring plan to reduce future operating expenses and further align resources around its long-term business strategy. The restructuring provided for a reduction of the Company’s global workforce by approximately 17% and the consolidation of certain leased office facilities. Under the first quarter 2017 restructuring plan, the Company recorded restructuring charges of $21.7 million, including $10.3 million related to severance, and $11.4 million related to accelerated depreciation and other charges. The actions associated with the first quarter 2017 restructuring plan were substantially completed by the fourth quarter of 2017. The restructuring charges recorded in 2018 are due to updated estimates as it relates to the consolidation of certain leased office facilities.



(in thousands)	Severance			Other			Total
Restructuring liability as of December 31, 2016	$	—		$	—		$	—
Restructuring charges	10,312			6,654			16,966
Cash paid	(9,509		)	(151		)	(9,660		)
Non-cash reductions	(803		)	(2,953		)	(3,756		)
Restructuring liability as of December 31, 2017	—			3,550			3,550
Restructuring charges	—			4,783			4,783
Cash paid	—			(3,293		)	(3,293		)
Non-cash charges	—			627			627
Restructuring liability as of December 31, 2018	$	—		$	5,667		$	5,667

Fourth quarter 2016 restructuring plan

On November 29, 2016, the Company approved a restructuring plan to reduce future operating expenses. The restructuring provided for a reduction of the Company’s global workforce of approximately 15%, the closure of the Company’s entertainment group to concentrate on its core business and the consolidation of certain leased office facilities. Under the fourth quarter 2016 restructuring plan, the Company recorded restructuring charges of $39.9 million, including $36.7 million related to severance, and $3.2 million related to accelerated depreciation and other charges. The actions associated with the fourth quarter 2016 restructuring plan were substantially completed by March 31, 2017.



(in thousands)	Severance			Other			Total
Restructuring liability as of December 31, 2015	$	—		$	—		$	—
Restructuring charges	18,893			879			19,772
Cash paid	(8,440		)	—			(8,440		)
Non-cash settlements	(793		)	—			(793		)
Restructuring liability as of December 31, 2016	9,660			879			10,539
Restructuring charges	2,134			1,055			3,189
Cash paid	(11,411		)	(1,884		)	(13,295		)
Non-cash settlements	17			—			17
Restructuring liability as of December 31, 2017	400			50			450
Restructuring charges	143			—			143
Cash paid	(244		)	—			(244		)
Restructuring liability as of December 31, 2018	$	299		$	50		$	349

First quarter 2016 restructuring plan

On January 12, 2016, the Company approved a restructuring plan that provided for a reduction in the Company’s global workforce of approximately 7%. Under the first quarter 2016 restructuring plan, the Company recorded restructuring charges of $6.5 million in the first quarter of 2016, which primarily included cash-based severance costs. The Company completed this plan at the end of the first quarter of 2016 and all costs have been paid. No charges were recorded in periods after March 31, 2016.