At December 31, 2018, we held the following debt securities and other investments, recorded at either fair value or cost:

	Amortized		Gross Unrealized					Carrying
(In thousands)	Cost		Gains		Losses			Value
Corporate bonds	$	20,777	$	19	$	(112	)	$	20,684
Municipal fixed-rate bonds		1,339		—		(26	)		1,313
Asset-backed bonds		5,230		5		(14	)		5,221
Mortgage/Agency-backed bonds		3,833		2		(44	)		3,791
U.S. government bonds		9,271		1		(66	)		9,206
Foreign government bonds		592		—		(8	)		584
Available-for-sale debt securities held at fair value	$	41,042	$	27	$	(270	)	$	40,799
Restricted investment held at cost									25,600
Other investments held at cost									397
Total carrying value of available-for-sale investments								$	66,796

At December 31, 2017, we held the following debt securities and other investments, recorded at either fair value or cost:

	Amortized		Gross Unrealized					Carrying
(In thousands)	Cost		Gains		Losses			Value
Corporate bonds	$	32,654	$	44	$	(155	)	$	32,543
Municipal fixed-rate bonds		2,902		2		(22	)		2,882
Asset-backed bonds		6,545		1		(20	)		6,526
Mortgage/Agency-backed bonds		5,554		1		(46	)		5,509
U.S. government bonds		14,477		—		(174	)		14,303
Foreign government bonds		725		5		—			730
Available-for-sale debt securities held at fair value	$	62,857	$	53	$	(417	)	$	62,493
Restricted investment held at cost									27,800
Other investments held at cost									547
Total carrying value of available-for-sale investments								$	90,840

As of December 31, 2018, our debt securities had the following contractual maturities:

(In thousands)	Corporate bonds		Municipal fixed-rate bonds		Asset-backed bonds		Mortgage / Agency-backed bonds		U.S. government bonds		Foreign government bonds
Less than one year	$	2,127	$	176	$	943	$	—	$	—	$	—
One to two years		11,557		208		401		—		6,714		285
Two to three years		6,831		929		193		425		—		299
Three to five years		169		—		2,433		853		2,492		—
Five to ten years		—		—		260		6		—		—
More than ten years		—		—		991		2,507		—		—
Total	$	20,684	$	1,313	$	5,221	$	3,791	$	9,206	$	584

Actual maturities may differ from contractual maturities as some borrowers have the right to call or prepay obligations with or without call or prepayment penalties.

Realized gains and losses on sales of securities are computed under the specific identification method. The following table presents gross realized gains and losses related to our debt securities for the years ended December 31, 2018, 2017 and 2016:

Our investment policy provides limitations for issuer concentration, which limits, at the time of purchase, the concentration in any one issuer to 5% of the market value of our total investment portfolio.

The following table presents the breakdown of debt securities and other investments with unrealized losses at December 31, 2018:

	Continuous Unrealized Loss Position for Less than 12 Months					Continuous Unrealized Loss Position for 12 Months or Greater					Total
(In thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate bonds		11,129		(60	)		3,608		(52	)		14,737		(112	)
Municipal fixed-rate bonds		—		—			1,136		(26	)		1,136		(26	)
Asset-backed bonds		1,874		(2	)		1,257		(12	)		3,131		(14	)
Mortgage/Agency-backed bonds		1,021		(5	)		1,918		(39	)		2,939		(44	)
U.S. government bonds		6,527		(48	)		537		(18	)		7,064		(66	)
Foreign government bonds		584		(8	)		—		—			584		(8	)
Total	$	21,135	$	(123	)	$	8,456	$	(147	)	$	29,591	$	(270	)

The following table presents the breakdown of debt securities and other investments with unrealized losses at December 31, 2017:

	Continuous Unrealized Loss Position for Less than 12 Months					Continuous Unrealized Loss Position for 12 Months or Greater					Total
(In thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate bonds		16,015		(58	)		6,112		(97	)		22,127		(155	)
Municipal fixed-rate bonds		230		—			1,165		(22	)		1,395		(22	)
Asset-backed bonds		4,941		(17	)		179		(3	)		5,120		(20	)
Mortgage/Agency-backed bonds		3,062		(8	)		1,673		(38	)		4,735		(46	)
U.S. government bonds		2,754		(26	)		11,549		(148	)		14,303		(174	)
Total	$	27,002	$	(109	)	$	20,678	$	(308	)	$	47,680	$	(417	)

The decrease in unrealized losses during 2018, as reflected in the table above, results from changes in market positions associated with our fixed income portfolio.

Our marketable equity securities consist of publicly traded stocks or funds measured at fair value.

Prior to January 1, 2018, our marketable equity securities were classified as available-for-sale. Realized gains and losses on marketable equity securities were included in net investment gain (loss). Unrealized gains and losses were recognized in accumulated other comprehensive income, net of deferred taxes, on the balance sheet.

On January 1, 2018, we adopted ASU 2016-01, which requires us to measure all equity investments that do not result in consolidation and are not accounted for under the equity method at fair value, with any changes in fair value recognized in net investment gain (loss). Upon adoption, we reclassified $3.2 million of net unrealized gains related to marketable equity securities from accumulated other comprehensive income (loss) to opening retained earnings.

Realized and unrealized gains and losses for our marketable equity securities for the twelve months ended December 31, 2018 were as follows:

We have categorized our cash equivalents and our investments held at fair value into a three-level fair value hierarchy based on the priority of the inputs to the valuation technique for the cash equivalents and investments as follows: Level 1 - Values based on unadjusted quoted prices for identical assets or liabilities in an active market; Level 2 - Values based on quoted prices in markets that are not active or model inputs that are observable either directly or indirectly; Level 3 - Values based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs could include information supplied by investees.

	Fair Value Measurements at December 31, 2018 Using
(In thousands)	Fair Value		Quoted Prices in Active Market for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents
Money market funds	$	1,554	$	1,554	$	—	$	—
Cash equivalents		1,554		1,554		—		—
Available-for-sale debt securities
Corporate bonds		20,684		—		20,684		—
Municipal fixed-rate bonds		1,313		—		1,313		—
Asset-backed bonds		5,221		—		5,221		—
Mortgage/Agency-backed bonds		3,791		—		3,791		—
U.S. government bonds		9,206		9,206		—		—
Foreign government bonds		584		—		584		—
Marketable equity securities								—
Marketable equity securities – various industries		26,763		26,763		—		—
Equity in escrow		253		253		—		—
Deferred compensation plan assets		18,256		18,256		—		—
Available-for-sale securities		86,071		54,478		31,593		—
Total	$	87,625	$	56,032	$	31,593	$	—

	Fair Value Measurements at December 31, 2017 Using
(In thousands)	Fair Value		Quoted Prices in Active Market for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents
Money market funds	$	5,851	$	5,851	$	—	$	—
Commercial paper		3,999		—		3,999		—
Cash equivalents		9,850		5,851		3,999		—
Available-for-sale debt securities
Corporate bonds		32,543		—		32,543		—
Municipal fixed-rate bonds		2,882		—		2,882		—
Asset-backed bonds		6,526		—		6,526		—
Mortgage/Agency-backed bonds		5,509		—		5,509		—
U.S. government bonds		14,303		14,303		—		—
Foreign government bonds		730		—		730		—
Marketable equity securities
Marketable equity securities – various industries		35,662		35,662		—		—
Deferred compensation plan assets		19,883		19,883		—		—
Available-for-sale securities		118,038		69,848		48,190		—
Total	$	127,888	$	75,699	$	52,189	$	—

The fair value of our Level 2 securities is calculated using a weighted average market price for each security. Market prices are obtained from a variety of industry standard data providers, security master files from large financial institutions, and other third-party sources. These multiple market prices are used as inputs into a distribution-curve-based algorithm to determine the daily market value of each security.