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



	March 31, 2018	December 31, 2017
	($000 omitted)
Investments in:
Debt securities	645,768	671,441
Equity securities	33,645	37,914
	679,413	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 statement of operations 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 March 31, 2018 and December 31, 2017, the net unrealized investment gains relating to investments in equity securities held were $3.4 million and $5.8 million, respectively.

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



	March 31, 2018		December 31, 2017
	Amortized costs	Fair values	Amortized costs	Fair values
	($000 omitted)
Municipal	63,187	63,123	71,581	72,669
Corporate	347,713	345,966	351,477	357,933
Foreign	226,683	224,217	229,750	228,237
U.S. Treasury Bonds	12,839	12,462	12,838	12,602
	650,422	645,768	665,646	671,441

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

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



	March 31, 2018		December 31, 2017
	Gains	Losses	Gains	Losses
	($000 omitted)
Municipal	440	504	1,263	175
Corporate	3,115	4,862	6,953	497
Foreign	1,390	3,856	1,742	3,255
U.S. Treasury Bonds	—	377	—	236
	4,945	9,599	9,958	4,163

Debt securities as of March 31, 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	45,924	45,914
After one year through five years	357,596	356,396
After five years through ten years	206,149	202,527
After ten years	40,753	40,931
	650,422	645,768

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, 2018, were:



	Less than 12 months		More than 12 months		Total
	Losses	Fair values	Losses	Fair values	Losses	Fair values
	($000 omitted)
Municipal	234	25,959	270	5,612	504	31,571
Corporate	4,670	241,586	192	4,824	4,862	246,410
Foreign	2,052	122,531	1,804	38,663	3,856	161,194
U.S. Treasury Bonds	130	5,756	247	6,706	377	12,462
	7,086	395,832	2,513	55,805	9,599	451,637

The number of specific debt investment securities held in an unrealized loss position as of March 31, 2018 was 292, 33 securities of which were in unrealized loss positions for more than 12 months. 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