Basis of Presentation (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Finite-Lived Intangible Assets

We amortize finite-lived intangible assets over their estimated useful lives as follows.

	Basis of amortization	Amortization period (in years)
Customer relationships	Straight-line and accelerated(1)	8-17
Marketing assets	Straight-line	2-15
Acquired software and technology	Straight-line and accelerated(1)	5-14

(1)Certain of the customer relationships and acquired software and technology assets are amortized on an accelerated basis.

Accounts Receivable, Allowance for Credit Loss

Below is a summary of the changes in our allowance for credit losses.

Years ended December 31, (in thousands)	Balance at beginning of year		Provision/ adjustment		Write-off		Recovery		Balance at end of year
2020(1)	$	4,011	$	6,787	$	(2,363)	$	581	$	9,016
2019	1,345		2,476		(2,617)		679		1,883
2018	741		2,446		(2,663)		821		1,345

(1)Upon adoption of ASU 2016-13 at January 1, 2020, we reclassified certain balances previously disclosed within the allowance for sales returns to the allowance for credit losses, as these amounts reflect the credit risk associated with our accounts receivable. The amount reclassified was $2.1 million.

The increase in our allowance for credit losses during the year ended December 31, 2020 was primarily due to an increase in the aging of our receivables during the second and third quarters of 2020 associated with the COVID-19 pandemic. We saw some improvement in our customers' payment behavior during the fourth quarter. The amount of write-offs during the year ended December 31, 2020 was lower than the amount of write-offs during the same period in 2019 as we temporarily suspended sending past due customer accounts to collections during the second and third quarters due to payment delays related to COVID-19.

Allowance for sales returns

We maintain a reserve for returns and credits which is estimated based on several factors including historical experience, known credits yet to be issued, the aging of customer accounts and the nature of service level commitments. A considerable amount of judgment is required in assessing these factors. Provisions for sales returns and credits are charged against the related revenue items.

Below is a summary of the changes in our allowance for sales returns.

Years ended December 31, (in thousands)	Balance at beginning of year		Provision/ adjustment		Deduction		Balance at end of year
2020(1)	$	1,518	$	6,443	$	(6,685)	$	1,276
2019	3,377		6,232		(5,963)		3,646
2018	4,400		4,952		(5,975)		3,377

(1)As discussed above, we reclassified certain balances previously disclosed within the allowance for sales returns to the allowance for credit losses upon adoption of ASU 2016-13 at January 1, 2020. The amount reclassified was $2.1 million.