CONSOLIDATED FINANCIAL STATEMENTS' COMPONENTS

Depreciation, Amortization and Accretion

Depreciation, amortization and accretion consisted of the following for the periods stated:



	For the Year Ended December 31,
(Dollars in thousands)	2019			2018			2017
Depreciation
Leasehold improvements	$	63		$	232		$	234
Asset retirement costs	(766		)	(300		)	(388		)
Paging and computer equipment	6,526			7,397			8,024
Furniture, fixtures and vehicles	374			398			306
Total depreciation	6,197			7,727			8,176
Amortization	2,500			2,500			2,886
Accretion	552			542			562
Total depreciation, amortization and accretion expense	$	9,249		$	10,769		$	11,624

Accounts Receivable, net

Accounts receivable was recorded net of an allowance of $1.3 million and $1.7 million for the years ended December 31, 2019 and 2018, respectively. Accounts receivable, net includes $6.4 million and $8.7 million of unbilled receivables for the years ended December 31, 2019 and 2018, respectively. Unbilled receivables are defined as the Company's right to consideration in exchange for goods or services that we have transferred to the customer but have not yet billed for, generally as a result of contractual billing terms. The decrease in unbilled receivables was primarily due to an increase in billings for the year ended December 31, 2019.

Property and Equipment, net

Property and equipment, net consisted of the following for the periods stated:



	Useful Life (In Years)	For the Year Ended December 31,
(Dollars in thousands)	Useful Life (In Years)	2019			2018
Leasehold improvements	lease term	$	3,620		$	4,139
Asset retirement costs	1-5	1,922			2,021
Paging and computer equipment	1-5	96,562			98,401
Furniture, fixtures and vehicles	3-5	3,716			4,353
Total property and equipment		105,820			108,914
Accumulated depreciation		(97,820		)	(98,560		)
Total property and equipment, net		$	8,000		$	10,354

For purposes of assessing our asset retirement costs, we completed a review of the estimated useful life of our transmitter assets during the fourth quarter of 2019 (that are part of paging and computer equipment). This review was based on the results of our long-range planning and network rationalization process and indicated that the expected useful life of the last tranche of the transmitter assets was no longer appropriate. As a result of that review, the expected useful life of the final tranche of transmitter assets was extended from 2023 to 2024. This change resulted in a revision of the expected future depreciation expense for the transmitter assets and an immaterial impact to the consolidated financial statements beginning in 2020. We believe these estimates remain reasonable at the present time, but we can give no assurance that changes in technology, customer usage patterns, our financial condition, the economy or other factors would not result in changes to our transmitter decommissioning plans. Any further variations from our estimates could result in a change in the expected useful lives of the underlying transmitter assets and operating results could differ in the future by any difference in depreciation expense. The extension of the depreciable life was accounted for as a change in accounting estimate.