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



	September 30, 2018	December 31, 2017
	($000 omitted)
Investments in:
Debt securities	624,422	671,441
Equity securities	37,667	37,914
	662,089	709,355

Investments in debt securities are classified as available-for-sale and the net unrealized gains and losses on such investments, net of applicable deferred taxes, are included as a component of AOCI within stockholders' equity. As a result of the Company's adoption of ASU 2016-01 (as discussed in Note 1-D), fair value changes relating to investments in equity securities are recognized as part of investment and other (losses) gains - net in the condensed consolidated statement of income and comprehensive income beginning on January 1, 2018. Previously, the investments in equity securities, which consist of common stocks and master limited partnership interests, were accounted for similar to investments in debt securities.

As of September 30, 2018 and December 31, 2017, the net unrealized investment gains relating to investments in equity securities held were $7.0 million and $5.8 million, respectively.

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



	September 30, 2018		December 31, 2017
	Amortized costs	Fair values	Amortized costs	Fair values
	($000 omitted)
Municipal	62,097	61,703	71,581	72,669
Corporate	346,429	340,919	351,477	357,933
Foreign	213,559	209,329	229,750	228,237
U.S. Treasury Bonds	12,948	12,471	12,838	12,602
	635,033	624,422	665,646	671,441

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

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



	September 30, 2018		December 31, 2017
	Gains	Losses	Gains	Losses
	($000 omitted)
Municipal	261	655	1,263	175
Corporate	2,045	7,555	6,953	497
Foreign	1,115	5,345	1,742	3,255
U.S. Treasury Bonds	—	477	—	236
	3,421	14,032	9,958	4,163

Debt securities as of September 30, 2018 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	48,839	48,844
After one year through five years	364,717	359,727
After five years through ten years	182,578	177,919
After ten years	38,899	37,932
	635,033	624,422

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 September 30, 2018, were:



	Less than 12 months		More than 12 months		Total
	Losses	Fair values	Losses	Fair values	Losses	Fair values
	($000 omitted)
Municipal	314	33,036	341	6,808	655	39,844
Corporate	6,862	266,231	693	15,359	7,555	281,590
Foreign	1,242	70,048	4,103	104,795	5,345	174,843
U.S. Treasury Bonds	150	4,277	327	8,088	477	12,365
	8,568	373,592	5,464	135,050	14,032	508,642

The number of specific debt investment holdings held in an unrealized loss position as of September 30, 2018 was 334. Of these securities, 83 securities were in unrealized loss positions for more than 12 months. The increased gross unrealized losses on corporate and foreign debt securities were primarily driven by increases in the overall rate environment, while the decline in value of the Canadian dollar against the U.S. dollar also contributed to higher gross unrealized losses on foreign debt securities. 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	58	17,023	117	5,784	175	22,807
Corporate	386	81,632	111	4,926	497	86,558
Foreign	1,528	116,130	1,727	39,031	3,255	155,161
U.S. Treasury Bonds	53	5,830	183	6,772	236	12,602
	2,025	220,615	2,138	56,513	4,163	277,128