Our financial assets and (liabilities) carried at fair value measured on a recurring basis as of March 31, 2020 and December 31, 2019, consisted of the following (in thousands):

(1)	The fair value of the interest rate contracts is determined using Level 2 fair value inputs and is recorded as other long-term assets or other long-term obligations in the consolidated balance sheets.

(2)

The fair value of the foreign currency contract assets (including those designated as hedging instruments and those not designated as hedging instruments) is determined using Level 2 fair value inputs and is recorded as prepaid expenses and other current assets or other long-term assets in the consolidated balance sheets.

(3)

The fair value of the foreign currency contract liabilities (including those designated as hedging instruments and those not designated as hedging instruments) is determined using Level 2 fair value inputs and is recorded as accrued expenses or other long-term obligations in the consolidated balance sheets.

Certain of our business combinations involve the potential for the payment of future contingent consideration, generally based on a percentage of future product sales or upon attaining specified future revenue or other milestones. See Note 4 for further information regarding these acquisitions. The contingent consideration liability is re-measured at the estimated fair value at the end of each reporting period with the change in fair value recognized within operating expenses in the accompanying consolidated statements of income (loss) for such period. We measure the initial liability and re-measure the liability on a recurring basis using Level 3 inputs as defined under authoritative guidance for fair value measurements.

Changes in the fair value of our contingent consideration liabilities during the three-month periods ended March 31, 2020 and 2019, consisted of the following (in thousands):


	Three Months Ended
	March 31,
	2020		2019
Beginning balance	$	76,709	$	82,236
Contingent consideration expense ⁽¹⁾		4,897		775
Contingent payments made		(12,754)		(554)
Effect of foreign exchange		17		—
Ending balance	$	68,869	$	82,457
(1) There were no fair value adjustments recorded to OCI for the three months ended March 31, 2020

As of March 31, 2020, approximately $57.6 million in contingent consideration liability was included in other long-term obligations and approximately $11.3 million in contingent consideration liability was included in accrued expenses in our consolidated balance sheet. As of December 31, 2019, approximately $48.1 million in contingent consideration liability was included in other long-term obligations and approximately $28.6 million in contingent consideration liability was included in accrued expenses in our consolidated balance sheet. Cash paid to settle the contingent consideration liability recognized at fair value as of the applicable acquisition date (including measurement-period adjustments) has been reflected as a cash outflow from financing activities in the accompanying consolidated statements of cash flows.

During the year ended December 31, 2016, we sold an equity investment for cash and for the right to receive additional payments based on various contingent milestones. We determined the fair value of the contingent payments using Level 3 inputs defined under authoritative guidance for fair value measurements, and we recorded a contingent receivable asset. During the three-month period ended March 31, 2019, we recorded a gain on the contingent receivable of approximately $20,000. As of December 31, 2019, the contingent receivable was settled in full and there was no balance remaining to collect.

The recurring Level 3 measurement of our contingent consideration liabilities included the following significant unobservable inputs at March 31, 2020 and December 31, 2019 (amounts in thousands):


	Fair value at
	March 31,		Valuation
Contingent consideration liability	2020		technique	Unobservable inputs	Range	Weighted Average⁽¹⁾
Revenue-based royalty payments contingent liability	$	8,053	Discounted cash flow	Discount rate	12% - 24%	15.4%
				Projected year of payments	2020-2034	2026

Revenue milestones contingent liability	$	58,116	Monte Carlo simulation	Discount rate	9% - 14.5%	10.9%
				Projected year of payments	2020-2023	2022

Regulatory approval contingent liability	$	2,700	Scenario-based method	Discount rate	6.6%
				Probability of milestone payment	65%
				Projected year of payment	2022
⁽¹⁾ Unobservable inputs were weighted by the relative fair value of the instruments. No weighted average is reported for unobservable inputs related to a single financial asset or liability.


	Fair value at
	December 31,		Valuation
Contingent consideration liability	2019		technique	Unobservable inputs	Range
Revenue-based royalty payments contingent liability	$	7,710	Discounted cash flow	Discount rate	13% - 24%
				Projected year of payments	2020-2034

Revenue milestones contingent liability	$	66,114	Monte Carlo simulation	Discount rate	9% - 13.5%
				Projected year of payments	2020-2023

Regulatory approval contingent liability	$	2,885	Scenario-based method	Discount rate	2.4%
				Probability of milestone payment	65%
				Projected year of payment	2022

The contingent consideration liability is re-measured to fair value each reporting period. Significant increases or decreases in projected revenues, based on our most recent internal operational budgets and long-range strategic plans, discount rates or the time until payment is made would have resulted in a significantly lower or higher fair value measurement. Our determination of the fair value of the contingent consideration liability could change in future periods based upon our ongoing evaluation of these significant unobservable inputs. We intend to record any such change in fair value to operating expenses in our consolidated statements of income (loss).

Fair Value of Other Financial Instruments

The carrying amount of cash and cash equivalents, receivables, and trade payables approximate fair value because of the immediate, short-term maturity of these financial instruments. Our long-term debt re-prices frequently due to variable rates and entails no significant changes in credit risk and, as a result, we believe the fair value of long-term debt approximates carrying value. The fair value of assets and liabilities whose carrying value approximates fair value is determined using Level 2 inputs, with the exception of cash and cash equivalents, which use Level 1 inputs.

We recognize or disclose the fair value of certain assets, such as non-financial assets, primarily property and equipment, intangible assets and goodwill in connection with impairment evaluations. All our nonrecurring valuations use significant unobservable inputs and therefore fall under Level 3 of the fair value hierarchy. During the three-month period ended March 31, 2020, we recorded impairment charges of approximately $359,000, related to certain property and equipment associated with our sale of the NvisionVLE® Imaging System under our distribution agreement with NinePoint Medical, Inc. (“NinePoint”). In addition, during the three-month periods ended March 31, 2020 and 2019, we had losses of approximately $81,000 and $211,000, respectively, related to the measurement of other non-financial assets at fair value on a nonrecurring basis subsequent to their initial recognition.

Our equity investments in privately held companies, including options to acquire these companies, were $14.5 million and $17.1 million at March 31, 2020 and December 31, 2019, respectively. We analyze our investments in privately-held companies to determine if they should be accounted for using the equity method based on our ability to exercise significant influence over operating and financial policies of the investment. Investments not accounted for under the equity method of accounting are accounted for at cost minus impairment, if applicable, plus or minus changes in valuation resulting from observable transactions for identical or similar investments. During the three-month period ended March 31, 2020 we recorded charges of $3.5 million due to our write-off of our purchase option to acquire Bluegrass Vascular due to our decision not to exercise our option to purchase the business.

Our outstanding long-term notes receivable, including accrued interest, and in 2020 our allowance for current expected credit losses, were approximately $2.1 million and $2.7 million as of March 31, 2020 and December 31, 2019, respectively. As of March 31, 2020, we recognized an allowance for current expected credit losses of $670,000 associated with these notes receivable and our contractual obligation to extend credit to Selio. We assess the allowance for current expected credit losses on an individual security basis, due to the limited number of securities, using a probability of default model,

which is based on relevant information about past events, including historical experience, current conditions and reasonable and supportable forecasts that affect the expected collectability of securities. During the first quarter of 2020, we adjusted the probability of default for all securities for a period of one year due to changes in current macroeconomic conditions and our expectations of collectability.

The table below presents a rollforward for the period ended March 31, 2020 of the allowance for current expected credit losses on our notes receivable (in thousands):


	Three Months Ended
	March 31, 2020
Beginning balance	$	—
Cumulative effect adjustment upon adoption of ASU 2016-13, Credit Losses		575
Provision for credit loss expense		95
Ending balance	$	670