Authoritative guidelines require the categorization of assets and liabilities into three levels based upon the assumptions (inputs) used to price the assets or liabilities. Level 1 provides the most reliable measure of fair value, whereas Level 3 generally requires significant management judgment. The three levels are defined as follows:

As of June 30, 2019, the fair values of our financial assets and liabilities were categorized as follows:


	Total		Level 1		Level 2		Level 3
Assets
Foreign exchange contracts ⁽¹⁾	$	157	$	—	$	157	$	—
Cross currency swap contract ⁽¹⁾		109		—		109		—
Total assets at fair value	$	266	$	—	$	266	$	—
Liabilities
Foreign exchange contracts ⁽¹⁾	$	736	$	—	$	736	$	—
Contingent consideration obligation		3,000		—		—		3,000
Cross currency swap contract ⁽¹⁾		73		—		73		—
Total liabilities at fair value	$	3,809	$	—	$	809	$	3,000

As of December 31, 2018, the fair values of our financial assets and liabilities were categorized as follows:


	Total		Level 1		Level 2		Level 3
Assets
Foreign exchange contracts ⁽¹⁾	$	259	$	—	$	259	$	—
Total assets at fair value	$	259	$	—	$	259	$	—
Liabilities
Foreign exchange contracts ⁽¹⁾	$	331	$	—	$	331	$	—
Cross currency swap contract⁽¹⁾		1,040		—		1,040		—
Total liabilities at fair value	$	1,371	$	—	$	1,371	$	—

(1)	Market approach valuation technique based on observable market transactions of spot and forward rates.

The carrying amounts of our other current financial instruments such as cash and equivalents, accounts and notes receivable, notes payable and current maturities of long-term obligations approximate fair value due to the short-term maturity of the instruments. We consider our long-term obligations a Level 2 liability and utilize the market approach valuation technique based on interest rates that are currently available to us for issuance of debt with similar terms and maturities. The estimated fair value of our long-term obligations was $1.1 billion as of June 30, 2019 and December 31, 2018. As discussed in Note 18 – Acquisitions, we have a contingent consideration obligation to the selling shareholders of Gateway Analytical (“Gateway”) in connection with the Gateway Acquisition (as defined herein) based on 2020 and 2022 performance targets defined by the purchase agreement. We consider this a Level 3 liability and on a quarterly basis we assess the projected results for the acquired business in comparison to the earnout targets and adjust the liability accordingly.