INVESTMENTS

Debt Securities

Investments in debt securities at the end of each period were as follows (in millions):



	March 31, 2019									December 31, 2018
Held-to-maturity	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Bank time deposits	$	30.0	$	—	$	—		$	30.0	$	20.0	$	—	$	—			$	20.0

Available-for-sale
Commercial paper	$	36.0	$	—	$	—		$	36.0	$	56.7	$	—	$	—			$	56.7
U.S. government and agency securities	79.7		0.2		(0.4		)	79.5		79.7		0.2		(0.7		)		79.2
Foreign government bonds	1.7		—		—			1.7		1.7		—		—				1.7
Asset-backed securities	102.2		0.3		(0.3		)	102.2		110.6		0.1		(0.5		)		110.2
Corporate debt securities	432.2		1.0		(1.5		)	431.7		459.8		0.1		(4.3		)		455.6
Municipal securities	2.8		—		—			2.8		2.8		—		—				2.8
Total	$	654.6	$	1.5	$	(2.2	)	$	653.9	$	711.3	$	0.4	$	(5.5	)		$	706.2

The cost and fair value of investments in debt securities, by contractual maturity, as of March 31, 2019 were as follows:



	Held-to-Maturity				Available-for-Sale
	Cost		Fair Value		Cost		Fair Value
	(in millions)
Due in 1 year or less	$	30.0	$	30.0	$	224.5	$	223.8
Due after 1 year through 5 years	—		—		340.9		340.9
Instruments not due at a single maturity date	—		—		89.2		89.2
	$	30.0	$	30.0	$	654.6	$	653.9

Actual maturities may differ from the contractual maturities due to call or prepayment rights.

The following tables present gross unrealized losses and fair values for those investments that were in an unrealized loss position as of March 31, 2019 and December 31, 2018, aggregated by investment category and the length of time that individual securities have been in a continuous loss position (in millions):



	March 31, 2019
	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
U.S. government and agency securities	$	—	$	—		$	56.7	$	(0.4	)	$	56.7	$	(0.4	)
Asset-backed securities	—		—			53.7		(0.3		)	53.7		(0.3		)
Corporate debt securities	56.1		(0.2		)	189.1		(1.3		)	245.2		(1.5		)
	$	56.1	$	(0.2	)	$	299.5	$	(2.0	)	$	355.6	$	(2.2	)



	December 31, 2018
	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
U.S. government and agency securities	$	0.7	$	(0.1	)	$	56.5	$	(0.6	)	$	57.2	$	(0.7	)
Asset-backed securities	4.0		0.1			61.3		(0.6		)	65.3		(0.5		)
Corporate debt securities	177.4		(1.1		)	203.7		(3.2		)	381.1		(4.3		)
	$	182.1	$	(1.1	)	$	321.5	$	(4.4	)	$	503.6	$	(5.5	)

Investments in Unconsolidated Affiliates

The Company has a number of equity investments in privately and publicly held companies. Investments in these unconsolidated affiliates are recorded in "Long-term Investments" on the consolidated condensed balance sheets, and are as follows:



	March 31, 2019			December 31, 2018
	(in millions)
Equity method investments
Cost	$	10.3		$	9.1
Equity in losses	(4.8		)	(4.7		)
Carrying value of equity method investments	5.5			4.4
Equity securities
Carrying value of non-marketable equity securities	18.1			18.1
Total investments in unconsolidated affiliates	$	23.6		$	22.5

Non-marketable equity securities consist of investments in privately held companies without readily determinable fair values, and are reported at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer. The Company did not record any upward or downward adjustments during the three months ended March 31, 2019. As of March 31, 2019, the Company had recorded accumulated upward adjustments of $1.7 million based on observable price changes, and accumulated downward adjustments of $1.9 million due to impairment and observable price changes.

During the three months ended March 31, 2019, the gross realized gains or losses from sales of available-for-sale investments were not material.