
	March 31, 2020		December 31, 2019
	(in millions)
Short-term investments:
Equity investment security	$	27	$	26
Held-to-maturity investment securities	321		287
Time deposits ⁽¹⁾	48		466
Total short-term investments	$	396	$	779


Long-term investments:
Equity and cost method investments	$	40	$	17
Time deposits ⁽¹⁾	$	393	$	—
Total long-term investments	$	433	$	17

(1)As of March 31, 2020, $393 million in restricted time deposits were classified as long-term. As of December 31, 2019, $414 million in restricted time deposits were classified as short-term. See Note 8.

Our equity investment security is a U.S. dollar denominated investment in an open-ended mutual fund. Realized and unrealized gains and losses were immaterial for the three months ended March 31, 2020 and 2019.

Our held-to-maturity investment securities consist of Indian rupee denominated investments primarily in commercial paper, international corporate bonds and government debt securities. Our investment guidelines are to purchase securities that are investment grade at the time of acquisition. The basis for the measurement of fair value of our held-to-maturity investments is Level 2 in the fair value hierarchy.

The amortized cost and fair value of our held-to-maturity investment securities were as follows:


	March 31, 2020						December 31, 2019
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(in millions)
Short-term investments, due within one year:
Corporate and other debt securities	$	146	$	146	$	101	$	101
Commercial paper	175		175		186		186
Total short-term held-to-maturity investments	$	321	$	321	$	287	$	287

The fair value and related unrealized losses of held-to-maturity investment securities in a continuous unrealized loss position for less than 12 months and for 12 months or longer were as follows as of March 31, 2020:


	Less than 12 Months						12 Months or More						Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
	(in millions)

Corporate and other debt securities	$	100	$	—	$	—	$	—	$	100	$	—
Commercial paper	49		—		—		—		49		—



Total	$	149	$	—	$	—	$	—	$	149	$	—


	Less than 12 Months						12 Months or More						Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
	(in millions)
Corporate and other debt securities	$	42	$	—	$	—	$	—	$	42	$	—
Commercial paper	70		—		—		—		70		—
Total	$	112	$	—	$	—	$	—	$	112	$	—

We monitor the credit ratings of the securities in our portfolio on an ongoing basis and evaluate the need for an allowance for expected credit losses. The securities in our portfolio are highly rated and short-term in nature. Historically, we have not had any impairment losses on our portfolio. As of March 31, 2020, $116 million of corporate and other debt securities were rated AAA and the remaining $30 million were rated AA+. Commercial paper securities were rated A-1+.

During the three months ended March 31, 2020 and the year ended December 31, 2019, there were no transfers of investments between our available-for-sale and held-to-maturity investment portfolios.

During the first quarter of 2020, we acquired a $26 million equity method investment in the technology sector. As of March 31, 2020 and December 31, 2019, we had equity method investments of $37 million and $9 million, respectively and cost method investments of $3 million and $8 million, respectively.