Use of Estimates in Preparation of Financial Statements. The preparation of the accompanying Financial Statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of our Financial Statements, and the reported amounts of revenue and expenses during the reporting periods. Actual results could differ from those estimates.

Revenue. The majority of our future revenue is related to our revenue management solution client contracts that include variable consideration dependent upon a series of monthly volumes and/or daily usage of services and have contractual terms ending from 2020 through 2028. Our client contracts may also include guaranteed minimums and fixed monthly or annual fees. As of September 30, 2020, our aggregate amount of the transaction price allocated to the remaining performance obligations is approximately $1 billion, which is made up of fixed fee consideration and guaranteed minimums expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied). We expect to recognize approximately 70% of this amount by the end of 2022, with the remaining amount recognized by the end of 2028. We have excluded from this amount variable consideration expected to be recognized in the future related to performance obligations that are unsatisfied.

The nature, amount, timing, and uncertainty of our revenue and how revenue and cash flows are affected by economic factors is most appropriately depicted by geographic region (using the location of the client as the basis of attributing revenue to the individual regions) as follows (in thousands):

	Quarter Ended				Nine Months Ended
	September 30,				September 30,
	2020		2019		2020		2019
Americas (principally the U.S.)	$	210,864	$	218,694	$	637,787	$	643,814
Europe, Middle East, and Africa		23,429		23,284		66,595		70,516
Asia Pacific		9,815		9,436		25,664		27,733
Total revenue	$	244,108	$	251,414	$	730,046	$	742,063

Deferred revenue recognized during the quarters ended September 30, 2020 and 2019 was $6.1 million and $5.7 million, respectively, and during the nine months ended September 30, 2020 and 2019 was $33.4 million and $35.5 million, respectively.

Cash and Cash Equivalents. We consider all highly liquid investments with original maturities of three months or less at the date of the purchase to be cash equivalents. As of September 30, 2020 and December 31, 2019, our cash equivalents consist primarily of institutional money market funds, commercial paper, and time deposits held at major banks.

As of September 30, 2020 and December 31, 2019, we had $1.6 million and $2.7 million, respectively, of restricted cash that serves to collateralize outstanding letters of credit. This restricted cash is included in cash and cash equivalents in our Condensed Consolidated Balance Sheets (“Balance Sheets” or “Balance Sheet”).

Short-term Investments and Other Financial Instruments. Our financial instruments as of September 30, 2020 and December 31, 2019 include cash and cash equivalents, short-term investments, accounts receivable, accounts payable, and debt. Because of their short maturities, the carrying amounts of cash equivalents, accounts receivable, and accounts payable approximate their fair value.

Our short-term investments and certain of our cash equivalents are considered “available-for-sale” and are reported at fair value in our Balance Sheets, with unrealized gains and losses, net of the related income tax effect, excluded from earnings and reported in a separate component of stockholders’ equity. Realized and unrealized gains and losses were not material in any period presented.

Primarily all short-term investments held by us as of September 30, 2020 and December 31, 2019 have contractual maturities of less than two years from the time of acquisition. Our short-term investments as of September 30, 2020 and December 31, 2019 consisted almost entirely of fixed income securities. Proceeds from the sale/maturity of short-term investments for the nine months ended September 30, 2020 and 2019 were $37.7 million and $38.0 million, respectively.

Our short-term investments as of September 30, 2020 and December 31, 2019 were $37.6 million and $26.1 million, respectively.

The following table represents the fair value hierarchy based upon three levels of inputs, of which Levels 1 and 2 are considered observable and Level 3 is unobservable, for our financial assets measured at fair value (in thousands):

	September 30, 2020						December 31, 2019
	Level 1		Level 2		Total		Level 1		Level 2		Total
Cash equivalents:
Money market funds	$	28,548	$	—	$	28,548	$	4,847	$	—	$	4,847
Commercial paper		—		6,098		6,098		—		26,964		26,964
Short-term investments:
Corporate debt securities		—		35,432		35,432		—		22,159		22,159
Asset-backed securities		—		2,173		2,173		—		3,950		3,950
Total	$	28,548	$	43,703	$	72,251	$	4,847	$	53,073	$	57,920

Valuation inputs used to measure the fair values of our money market funds and corporate equity securities were derived from quoted market prices. The fair values of all other financial instruments are based upon pricing provided by third-party pricing services. These prices were derived from observable market inputs.

We have chosen not to measure our debt at fair value, with changes recognized in earnings each reporting period. The following table indicates the carrying value (par value for convertible debt) and estimated fair value of our debt as of the indicated periods (in thousands):

	September 30, 2020				December 31, 2019
	Carrying		Fair		Carrying		Fair
	Value		Value		Value		Value
2018 Credit Agreement (carrying value including current maturities)	$	129,375	$	129,375	$	136,875	$	136,875
2016 Convertible debt (par value)		230,000		240,350		230,000		262,775

The fair value for our credit agreement was estimated using a discounted cash flow methodology, while the fair value for our convertible debt was estimated based upon quoted market prices or recent sales activity, both of which are considered Level 2 inputs.

Equity Method Investment. During the nine months ended September 30, 2020, we made an additional $1.5 million investment in a payment technology and services company. As of September 30, 2020, we held a 15% noncontrolling interest with a carrying value of $8.0 million.