Revenue and Accounts Receivable, Net

Revenue Details

The pattern of revenue recognition was as follows:



	Three Months Ended March 31,
(In thousands)	2020		2019
Goods and services transferred at a point in time	$	117,058	$	136,338
Goods and services transferred over time	34,720		47,825
Net sales	$	151,778	$	184,163

Our net sales to external customers by geographic area were as follows:

Specific identification of the customer billing location was the basis used for attributing revenues from external customers to geographic areas.

Net sales to the following customers totaled more than 10% of our net sales:

⁽¹⁾ Sales associated with this customer did not total more than 10% of our net sales for the indicated period.

Accounts Receivable, Net

Accounts receivable, net were as follows:

Allowance for Bad Debts

Changes in the allowance for bad debts were as follows:



(In thousands)	Three Months Ended March 31,
(In thousands)	2020			2019
Balance at beginning of period	$	1,492		$	1,121
Additions to costs and expenses	237			3
(Write-offs)/Foreign exchange effects	(48		)	(4		)
Balance at end of period	$	1,681		$	1,120

Trade receivables associated with these significant customers that totaled more than 10% of our accounts receivable, net were as follows:


⁽¹⁾	Trade receivables associated with this customer did not total more than 10% of our accounts receivable, net for the indicated period.