Investments in debt and equity securities. The total fair values of the Company's investments in debt and equity securities are as follows:



	March 31, 2019	December 31, 2018
	($000 omitted)
Investments in:
Debt securities	590,115	602,020
Equity securities	37,533	33,997
	627,648	636,017

As of March 31, 2019 and December 31, 2018, the net unrealized investment gains relating to investments in equity securities held were $6.6 million and $2.9 million, respectively.

The amortized costs and fair values of investments in debt securities are as follows:



	March 31, 2019		December 31, 2018
	Amortized costs	Fair values	Amortized costs	Fair values
	($000 omitted)
Municipal	60,467	61,348	61,779	61,934
Corporate	322,993	325,918	333,289	328,495
Foreign	195,177	196,430	200,667	198,938
U.S. Treasury Bonds	6,533	6,419	12,951	12,653
	585,170	590,115	608,686	602,020

Foreign debt securities consist of Canadian government and corporate bonds, United Kingdom treasury and corporate bonds, and Mexican government bonds.

Gross unrealized gains and losses on investments in debt securities are as follows:



	March 31, 2019		December 31, 2018
	Gains	Losses	Gains	Losses
	($000 omitted)
Municipal	945	64	482	327
Corporate	4,014	1,089	1,894	6,688
Foreign	2,336	1,083	1,402	3,131
U.S. Treasury Bonds	2	116	2	300
	7,297	2,352	3,780	10,446

Debt securities as of March 31, 2019 mature, according to their contractual terms, as follows (actual maturities may differ due to call or prepayment rights):



	Amortized costs	Fair values
	($000 omitted)
In one year or less	50,945	50,822
After one year through five years	326,286	328,615
After five years through ten years	176,344	178,348
After ten years	31,595	32,330
	585,170	590,115

Gross unrealized losses on investments in debt securities and the fair values of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at March 31, 2019, were:



	Less than 12 months		More than 12 months		Total
	Losses	Fair values	Losses	Fair values	Losses	Fair values
	($000 omitted)
Municipal	—	—	64	9,099	64	9,099
Corporate	28	9,652	1,061	117,827	1,089	127,479
Foreign	36	16,905	1,047	88,177	1,083	105,082
U.S. Treasury Bonds	—	—	116	6,310	116	6,310
	64	26,557	2,288	221,413	2,352	247,970

The number of specific debt investment holdings held in an unrealized loss position as of March 31, 2019 was 151. Of these securities, 138 were in unrealized loss positions for more than 12 months. During 2019, the overall gross unrealized losses on debt securities decreased compared to the prior year-end, primarily due to the decrease in the overall interest rate environment which improved the market values of investments. Since the Company does not intend to sell and will more likely than not maintain each investment security until its maturity or anticipated recovery, and no significant credit risk is deemed to exist, these investments are not considered as other-than-temporarily impaired. The Company believes its investment portfolio is diversified and expects no material loss to result from the failure to perform by issuers of the debt securities it holds. Investments made by the Company are not collateralized.



	Less than 12 months		More than 12 months		Total
	Losses	Fair values	Losses	Fair values	Losses	Fair values
	($000 omitted)
Municipal	91	13,366	236	11,645	327	25,011
Corporate	4,416	201,965	2,272	71,044	6,688	273,009
Foreign	158	11,424	2,973	137,793	3,131	149,217
U.S. Treasury Bonds	—	—	300	12,544	300	12,544
	4,665	226,755	5,781	233,026	10,446	459,781