Condensed consolidated financial statement details

The following sections and tables provide details of selected balance sheet items.

Inventory



(in thousands)	September 30, 2016		December 31, 2015
Components	$	35,097	$	9,476
Finished goods	110,134		178,756
Total inventory	$	145,231	$	188,232

Property and equipment, net



(in thousands)	September 30, 2016			December 31, 2015
Leasehold improvements	$	48,019		$	40,841
Production, engineering and other equipment	40,991			25,174
Tooling	22,592			19,537
Computers and software	17,771			14,581
Furniture and office equipment	12,540			11,389
Construction in progress	2,317			4,632
Tradeshow equipment and other	7,409			4,136
Gross property and equipment	151,639			120,290
Less: Accumulated depreciation and amortization	(74,062		)	(50,240		)
Property and equipment, net	$	77,577		$	70,050

The Company has committed to plans to vacate and sublet certain leased office facilities. Changes in estimated useful life of associated leasehold improvements and office equipment are expected to result in accelerated depreciation expense of approximately $10 million, including $4.3 million recorded for the three months ended September 30, 2016 and $5.4 million ratably over an estimated remaining period of 11 months.

Intangible assets and goodwill



	September 30, 2016
(in thousands)	Gross carrying value		Accumulated amortization			Net carrying value
Purchased technology	$	48,634	$	(15,063	)	$	33,571
In-process research and development (IPR&D)	3,925		—			3,925
Total intangible assets	$	52,559	$	(15,063	)	$	37,496



	December 31, 2015
(in thousands)	Gross carrying value		Accumulated amortization			Net carrying value
Purchased technology	$	32,952	$	(8,540	)	$	24,412
IPR&D	6,615		—			6,615
Total intangible assets	$	39,567	$	(8,540	)	$	31,027

A summary of the Company’s IPR&D activity for the nine months ended September 30, 2016 is as follows:



(in thousands)	Total
Balance at December 31, 2015	$	6,615
IPR&D assets acquired	3,760
Technological feasibility achieved	(450		)
Asset impairment	(6,000		)
Balance at September 30, 2016	$	3,925

Purchased technology acquired in 2016 has an estimated useful life of four years. During the three months ended September 30, 2016, the Company recorded an impairment charge of $6.0 million to research and development expense for IPR&D assets acquired in 2015 that were abandoned in the third quarter of 2016. As of September 30, 2016, technological feasibility has not been established for the remaining IPR&D assets, which have no alternative future use and, as such, continue to be accounted for as indefinite-lived intangible assets.

Amortization expense was $6.5 million and $2.7 million in the nine months ended September 30, 2016 and 2015, respectively. At September 30, 2016, the expected amortization expense of amortizable intangible assets for future periods is as follows:



(in thousands)	Total
Year ending December 31,
2016 (remaining 3 months)	$	2,567
2017	9,506
2018	8,569
2019	7,786
2020	4,273
Thereafter	870
	$	33,571

The carrying amount of goodwill was $146.5 million and $57.1 million as of September 30, 2016 and December 31, 2015, respectively. The increase in 2016 was entirely attributable to the acquisitions described above in Note 2.

Accrued liabilities



(in thousands)	September 30, 2016		December 31, 2015
Accrued payables	$	73,084	$	60,738
Inventory received not billed	29,479		4,093
Employee related liabilities	33,935		26,491
Accrued sales incentives	19,637		29,298
Warranty liability	8,858		10,400
Customer deposits	6,520		8,877
Income taxes payable	1,979		7,536
Purchase order commitments	2,374		38,477
Other	8,039		6,536
Accrued liabilities	$	183,905	$	192,446