Fair value measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Financial instruments measured at fair value on recurring basis

As of March 31, 2018, financial instruments measured at fair value on a recurring basis are summarized below:

	Level 1	Level 2	Fair value measurements
	($000 omitted)
Investments in securities:
Debt securities:
Municipal	—	63,123	63,123
Corporate	—	345,966	345,966
Foreign	—	224,217	224,217
U.S. Treasury Bonds	—	12,462	12,462
Equity securities	33,645	—	33,645
	33,645	645,768	679,413

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

	Level 1	Level 2	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