The following summarizes property, equipment and software, net as of December 31, 2020 and 2019 (in thousands):


	December 31,
	2020		2019
Warehouse equipment	$	—	$	5,144
Furniture and fixtures	5,005		9,113
Leasehold improvements	24,808		47,927
Office equipment	676		1,735
Purchased software	435		7,207
Computer hardware	121,307		143,118
Internally-developed software (1)	264,103		222,140
Total property, equipment and software, gross	416,334		436,384
Less: accumulated depreciation and amortization	(331,050)		(311,434)
Property, equipment and software, net	$	85,284	$	124,950

(1)The net carrying amount of internally-developed software was $57.9 million and $71.1 million as of December 31, 2020 and 2019.

Due to the triggering event and subsequent review of long-lived assets for impairment in the first quarter of 2020 described in Note 3, COVID-19 Pandemic, we recognized long-lived asset impairment of property, equipment and software, net of $15.2 million within our International segment related to our EMEA operations.

The assets that we deemed impaired were written down to fair value based on the discounted cash flow method that uses Level 3 inputs. The significant estimates used in the discounted cash flow models are the risk-

adjusted discount rates; forecasted revenue, cost of revenue and operating expenses; forecasted capital expenditures and working capital needs; weighted-average cost of capital; rates of long-term growth; and income tax rates.

The following table summarizes impairment for long-lived assets by asset type for the year ended December 31, 2020 (in thousands), of which $9.6 million is included in $22.4 million of Long-lived asset impairment and $5.6 million is included in $21.6 million of Restructuring and related charges on the consolidated statements of operations:


Long-Lived Asset Category	Impairment
Property, equipment and software, net
Furniture and fixtures	$	413
Leasehold improvements	8,419
Office equipment	198
Purchased software	14
Computer hardware	2,842
Capitalized software	304
Internally-developed software	2,988
Total	$	15,178

Depreciation and amortization expense on property, equipment and software is classified as follows in the accompanying consolidated statements of operations for the years ended December 31, 2020, 2019 and 2018 (in thousands):


	Year Ended December 31,
	2020		2019		2018
Service cost of revenue	$	28,443	$	28,917	$	28,102
Product cost of revenue	9,434		6,466		8,467
Selling, general and administrative	39,915		56,027		64,761
Total	$	77,792	$	91,410	$	101,330

The above amounts include amortization of internally-developed software of $58.8 million, $56.6 million and $53.9 million, and amortization expense on assets under finance leases of $6.7 million, $18.9 million and $30.2 million, for the years ended December 31, 2020, 2019 and 2018.