Accounts receivable are uncollateralized customer obligations arising from the sale of products or services. Accounts receivable have normal trade terms less than one year and are initially stated at the amounts billed to the customers. Accounts receivable are subsequently measured at amortized cost net of allowance for credit loss. As part of its analysis for implementation of the CECL standard as of January 1, 2020, the Company reviewed historical loss rates, customer payment trends and collection rates on customer balances. Estimated loss rates were developed using historical credit loss experience, adjusted for future expectations using probability-weighted assumptions about potential outcomes. Receivables are written off against the allowance for credit loss when it is probable that amounts will not be collected based on terms of the customer contracts, and subsequent recoveries reverse the previous write-off and apply to the receivable in the period recovered. The Company periodically evaluates the adequacy of its allowance for expected credit losses by comparing its actual historical write-offs to its previously recorded estimates.

The Company identified portfolio segments based on type of business, industry in which the customer operates and historical credit loss patterns. The following presents by portfolio segment Accounts receivable, net and the activity in the Allowance for credit loss for the six months ended June 30, 2020:

($ in thousands)	Commercial Services (Driver-billed) ⁽¹⁾			Commercial Services (All other)			Government Solutions			Total
Accounts Receivable, Net at January 1, 2020 ⁽²⁾	$	9,793		$	51,158		$	31,744		$	92,695

Allowance for credit loss at January 1, 2020 ⁽²⁾	$	5,272		$	1,406		$	1,778		$	8,456
Credit loss expense		2,744			6,256			1,723			10,723
Write-offs, net of recoveries		(5,449	)		(334	)		(466	)		(6,249	)
Allowance for credit loss at June 30, 2020	$	2,567		$	7,328		$	3,035		$	12,930

Accounts Receivable, Net at June 30, 2020	$	7,926		$	48,934		$	68,392		$	125,252

The estimated credit loss expense for the six months ended June 30, 2020 includes a specific provision of $3.5 million for accounts receivable due from one of our Commercial Services (All other) customers who filed for Chapter 11 bankruptcy.

Significant customers are those which represent more than 10% of the Company’s total revenue and accounts receivable. Revenue from one of the Government Solutions customers as a percent of total revenue is presented below for the three and six months ended June 30, 2020 and 2019, respectively:

	Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
City of New York Department of Transportation		40.5	%		12.4	%		31.6	%		10.4	%

The City of New York Department of Transportation represents 42.2% of accounts receivable, net as of June 30, 2020. Significant customer revenue generated through the Company’s Commercial Services partners as a percent of total revenue is presented below for the three and six months ended June 30, 2020 and 2019, respectively:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020	2019			2020			2019
Hertz Corporation	(1)		19.6	%		13.0	%		19.0	%
Avis Budget Group, Inc.	(1)		16.5	%	(1)				13.1	%
Enterprise Holdings, Inc.	(1)		13.5	%	(1)				13.7	%