Fair value measurements (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Financial instruments measured at fair value on recurring basis

As of June 30, 2017, financial instruments measured at fair value on a recurring basis are summarized below:

	Level 1	Level 2	Fair value measurements
	($000 omitted)
Investments available-for-sale:
Debt securities:
Municipal	—	73,601	73,601
Corporate	—	332,226	332,226
Foreign	—	200,669	200,669
U.S. Treasury Bonds	—	12,894	12,894
Equity securities	35,372	—	35,372
	35,372	619,390	654,762

As of December 31, 2016, financial instruments measured at fair value on a recurring basis are summarized below:

	Level 1	Level 2	Fair value measurements
	($000 omitted)
Investments available-for-sale:
Debt securities:
Municipal	—	72,432	72,432
Corporate	—	343,047	343,047
Foreign	—	167,027	167,027
U.S. Treasury Bonds	—	12,613	12,613
Equity securities	36,384	—	36,384
	36,384	595,119	631,503