Fair value measurements (Tables)

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Financial Instruments Measured at Fair Value on Recurring Basis

As of June 30, 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	—	62,022	62,022
Corporate	—	297,040	297,040
Foreign	—	161,346	161,346
U.S. Treasury Bonds	—	14,111	14,111
Equity securities	32,264	—	32,264
	32,264	534,519	566,783

As of December 31, 2014, 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	—	61,689	61,689
Corporate	—	308,691	308,691
Foreign	—	166,685	166,685
U.S. Treasury Bonds	—	14,802	14,802
Equity securities	28,236	—	28,236
	28,236	551,867	580,103