The following tables show our cash, cash equivalents, restricted cash, short-term and long-term available-for-sale marketable debt securities, by major security type, that are measured at fair value on a recurring basis and were categorized using the fair value hierarchy, as well as their classification on our unaudited condensed consolidated balance sheets, as of the periods presented (in millions):

	June 30, 2019
	Amortized Cost		Fair Value (2)		Cash, Cash Equivalents and Restricted Cash		Short-Term Marketable Securities		Long-Term Marketable Securities
Cash and restricted cash (1)	$	870	$	870	$	870	$	—	$	—
Level 1:
Money market funds		31		31		31		—		—
Level 2:
Commercial paper		65		65		—		65		—
Total	$	966	$	966	$	901	$	65	$	—

	December 31, 2018
	Amortized Cost		Fair Value (2)		Cash, Cash Equivalents and Restricted Cash		Short-Term Marketable Securities		Long-Term Marketable Securities
Cash and restricted cash (1)	$	522	$	522	$	522	$	—	$	—
Level 1:
Money market funds		128		128		128		—		—
Level 2:
Commercial paper		20		20		5		15		—
Total	$	670	$	670	$	655	$	15	$	—

Our cash and cash equivalents consist of cash on hand in global financial institutions, money market funds and marketable securities with maturities of 90 days or less at the date of purchase. Our short-term marketable securities include maturities that were greater than 90 days at the date purchased and have 12 months or less remaining at June 30, 2019 and December 31, 2018, respectively.

For assets and liabilities required to be reported at fair value, GAAP provides a hierarchy that prioritizes inputs to valuation techniques used to measure fair value into three broad levels:

Level 1—Valuations are based on quoted market prices for identical assets and liabilities in active markets.

Level 2—Valuations are based on observable inputs other than quoted market prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data.

Level 3—Valuations are based on unobservable inputs reflecting our own assumptions, consistent with reasonably available assumptions made by other market participants. These valuations require significant judgment.

We classify our money market funds and other marketable securities within Level 1 and Level 2 as we value these financial instruments using quoted market prices (Level 1) or alternative pricing sources (Level 2). The valuation technique we used to measure the fair value of money market funds was derived from quoted prices in active markets for identical assets or liabilities. Fair values for Level 2 marketable securities are considered “Level 2” valuations because they are obtained from independent pricing sources for identical or comparable instruments, rather than direct observations of quoted prices in active markets. Our procedures include controls to ensure that appropriate fair values are recorded, including comparing the fair values obtained from our independent pricing services against fair values obtained from another independent source.

There were no material realized gains or losses related to the sales of our marketable securities for both the three and six months ended June 30, 2019 and 2018. Realized gains and losses on the sale of securities are determined by specific identification of each security’s cost basis. We consider any unrealized loss position in our available-for-sale marketable debt securities to be temporary in nature and do not consider any of these investments other-than-temporarily impaired as of both June 30, 2019 and December 31, 2018.

We typically use forward contracts to reduce the effects of foreign currency exchange rate fluctuations on our cash flows primarily for the Euro versus the U.S. Dollar. Counterparties to our forward contracts consist of major international financial institutions. We monitor our positions and the credit ratings of the counterparties involved and, by policy limits, the amount of credit exposure to any one party. For the three and six months ended June 30, 2019 and 2018, respectively, our forward contracts have not been designated as hedges and generally had maturities of less than 90 days. We do not use derivatives for trading or speculative purposes.

Our outstanding or unsettled forward contracts were carried at fair value on our unaudited condensed consolidated balance sheets at June 30, 2019 and December 31, 2018. We measure the fair value of our outstanding or unsettled derivatives using Level 2 fair value inputs, as we use a pricing model that takes into account the contract terms as well as current foreign currency exchange rates in active markets. We recognized any gain or loss resulting from the change in fair value of our foreign currency forward contracts in interest income and other, net on our unaudited condensed consolidated statement of operations which was not material for both the three and six months ended June 30, 2019, and a net loss of $3 million for both the three and six months ended June 30, 2018.

The following table shows the notional principal amounts of our outstanding derivative instruments as of the periods presented:

Other financial instruments not measured at fair value on a recurring basis include accounts receivable and contract assets, accounts payable, deferred merchant payables, and accrued and other current liabilities. The carrying amount of these financial instruments approximate their fair value because of the short maturity of these instruments as reported on our unaudited condensed consolidated balance sheets as of June 30, 2019 and December 31, 2018.

In addition, we hold investments in equity securities of privately-held companies that do not have a readily determinable fair value. As of both June 30, 2019 and December 31, 2018, the total carrying value of our equity investments in these privately-held companies was $12 million and is included in other long-term assets on our unaudited condensed consolidated balance sheets. Our policy is to measure these investments at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Such observable price changes may include instances where the investee issues equity securities to new investors, thus creating a new indicator of fair value, as an example. On a quarterly basis, we perform a qualitative assessment considering impairment indicators to evaluate whether these investments are impaired and also monitor for any observable price changes. During the three and six months ended June 30, 2019 and 2018, we did not record any impairment loss on these equity investments or identify any observable price change indicators.

The Company did not have any material assets or liabilities measured at fair value on a recurring basis using the Level 3 unobservable inputs at both June 30, 2019 and December 31, 2018.