Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Financial instruments measured at fair value on recurring basis

At December 31, 2018, financial instruments measured at fair value on a recurring basis are summarized below:

	Level 1	Level 2	Level 3	Fair value measurements
	($000 omitted)
Investments in securities:
Debt securities:
Municipal	—	61,934	—	61,934
Corporate	—	328,495	—	328,495
Foreign	—	198,938	—	198,938
U.S. Treasury Bonds	—	12,653	—	12,653
Equity securities:	33,997	—	—	33,997
	33,997	602,020	—	636,017

At December 31, 2017, financial instruments measured at fair value on a recurring basis are summarized below:

	Level 1	Level 2	Level 3	Fair value measurements
	($000 omitted)
Investments in securities:
Debt securities:
Municipal	—	72,669	—	72,669
Corporate	—	357,933	—	357,933
Foreign	—	228,237	—	228,237
U.S. Treasury Bonds	—	12,602	—	12,602
Equity securities:	37,914	—	—	37,914
	37,914	671,441	—	709,355