Fair value measurements (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Financial Instruments Measured at Fair Value on Recurring Basis

As of March 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	—	72,397	72,397
Corporate	—	346,654	346,654
Foreign	—	161,484	161,484
U.S. Treasury Bonds	—	13,894	13,894
Equity securities	31,934	—	31,934
	31,934	594,429	626,363

As of December 31, 2015, 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	—	72,008	72,008
Corporate	—	309,461	309,461
Foreign	—	153,221	153,221
U.S. Treasury Bonds	—	13,906	13,906
Equity securities	31,253	—	31,253
	31,253	548,596	579,849