Investments in debt and equity securities (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Amortized costs and fair values

Amortized costs and fair values at December 31, follow:

	2017		2016
	Amortized costs	Fair values	Amortized costs	Fair values
	($000 omitted)
Debt securities:
Municipal	71,581	72,669	72,284	72,432
Corporate	351,477	357,933	338,365	343,047
Foreign	229,750	228,237	165,735	167,027
U.S. Treasury Bonds	12,838	12,602	12,795	12,613
Equity securities	32,132	37,914	30,255	36,384
	697,778	709,355	619,434	631,503

Gross unrealized gains and losses

Gross unrealized gains and losses at December 31, were:

	2017		2016
	Gains	Losses	Gains	Losses
	($000 omitted)
Debt securities:
Municipal	1,263	175	723	575
Corporate	6,953	497	6,871	2,189
Foreign	1,742	3,255	2,912	1,620
U.S. Treasury Bonds	—	236	4	186
Equity securities	6,367	585	6,800	671
	16,325	4,748	17,310	5,241

Debt securities according to contractual terms

Debt securities at December 31, 2017 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	35,974	36,092
After one year through five years	358,738	362,206
After five years through ten years	221,792	221,994
After ten years	49,142	51,149
	665,646	671,441

Gross unrealized losses on investments and fair values of related securities

Gross unrealized losses on investments 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 December 31, 2017, were:

	Less than 12 months		More than 12 months		Total
	Losses	Fair values	Losses	Fair values	Losses	Fair values
	($000 omitted)
Debt securities:
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
Equity securities:	555	6,475	30	860	585	7,335
	2,580	227,090	2,168	57,373	4,748	284,463

Gross unrealized losses on investments 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 December 31, 2016, were:

	Less than 12 months		More than 12 months		Total
	Losses	Fair values	Losses	Fair values	Losses	Fair values
	($000 omitted)
Debt securities:
Municipal	575	32,038	—	—	575	32,038
Corporate	2,189	119,965	—	—	2,189	119,965
Foreign	1,427	70,012	193	3,160	1,620	73,172
U.S. Treasury Bonds	186	11,847	—	—	186	11,847
Equity securities:	424	5,950	247	2,250	671	8,200
	4,801	239,812	440	5,410	5,241	245,222