In some instances, we incur third party costs that directly relate to the contract to fulfill the contract obligations. These fulfillment costs are capitalized and amortized consistent with how the related revenue is recognized. Changes in our deferred costs on contracts are as follows for the six months ended June 30:

	2019			2018
				(Restated)
Balance at beginning of year	$	3,746		$	1,780
Fulfillment costs incurred		5,821			5,039
Amortization of fulfillment costs		(7,717	)		(6,330	)
Balance at end of period	$	1,850		$	489

Typically, our mobilization services are paid by the customer at the beginning of the contract while the revenue is recognized as control transfers to the customer, which can result in deferred revenue. Normally all other revenue is billed as work progresses, which generally will not result in significant deferred revenue except in those cases where a large mobilization is required for the contract. Changes in our deferred revenue are as follows for the six months ended June 30:

	2019			2018
				(Restated)
Balance at beginning of year	$	4,357		$	1,477
Cash received, excluding amounts recognized as revenue from services		8,181			385
Amounts recognized as revenue from services		(8,098	)		(1,862	)
Balance at end of period	$	4,440		$	—

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
			(Restated)				(Restated)
North America	$	28,875	$	4,760	$	89,428	$	32,439
South America		702		12,123		752		21,567
Asia Pacific ⁽¹⁾		59,960		—		92,412		—
Total	$	89,537	$	16,883	$	182,592	$	54,006

As of June 30, 2019, we had $109.1 million of remaining performance obligations. We expect to recognize revenue of approximately 62% of these performance obligations in 2019 and the remaining approximately 38% in 2020.