Fair value measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Financial instruments measured at fair value on recurring basis

As of September 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	—	73,355	73,355
Corporate	—	342,760	342,760
Foreign	—	214,567	214,567
U.S. Treasury Bonds	—	12,721	12,721
Equity securities	36,279	—	36,279
	36,279	643,403	679,682

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