Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Balances Of Assets Measured At Fair Value On A Recurring Basis

The following tables present the balances of assets measured at fair value on a recurring basis by level within the fair value hierarchy.

	December 31, 2019
(dollars in thousands)	Level 1		Level 2		Level 3		Total
Assets:
Investments:
Fixed maturities, available-for-sale:
U.S. Treasury securities	$	—	$	284,786	$	—	$	284,786
U.S. government-sponsored enterprises	—		342,580		—		342,580
Obligations of states, municipalities and political subdivisions	—		4,189,882		—		4,189,882
Foreign governments	—		1,542,004		—		1,542,004
Commercial mortgage-backed securities	—		1,817,845		—		1,817,845
Residential mortgage-backed securities	—		888,073		—		888,073
Asset-backed securities	—		11,048		—		11,048
Corporate bonds	—		894,691		—		894,691
Total fixed maturities, available-for-sale	—		9,970,909		—		9,970,909
Equity securities:
Insurance, banks and other financial institutions	2,463,190		—		45,992		2,509,182
Industrial, consumer and all other	5,081,573		—		—		5,081,573
Total equity securities	7,544,763		—		45,992		7,590,755
Short-term investments, available-for-sale	1,093,799		102,449		—		1,196,248
Total investments	$	8,638,562	$	10,073,358	$	45,992	$	18,757,912

	December 31, 2018
(dollars in thousands)	Level 1		Level 2		Level 3		Total
Assets:
Investments:
Fixed maturities, available-for-sale:
U.S. Treasury securities	$	—	$	246,642	$	—	$	246,642
U.S. government-sponsored enterprises	—		359,322		—		359,322
Obligations of states, municipalities and political subdivisions	—		4,352,930		—		4,352,930
Foreign governments	—		1,559,604		—		1,559,604
Commercial mortgage-backed securities	—		1,650,199		—		1,650,199
Residential mortgage-backed securities	—		880,172		—		880,172
Asset-backed securities	—		19,408		—		19,408
Corporate bonds	—		974,911		—		974,911
Total fixed maturities, available-for-sale	—		10,043,188		—		10,043,188
Equity securities:
Insurance, banks and other financial institutions	1,876,811		—		53,728		1,930,539
Industrial, consumer and all other	3,790,406		—		—		3,790,406
Total equity securities	5,667,217		—		53,728		5,720,945
Short-term investments, available-for-sale	981,616		96,080		—		1,077,696
Total investments	$	6,648,833	$	10,139,268	$	53,728	$	16,841,829

Summary Of Changes In Level 3 Investments Measured At Fair Value On A Recurring Basis

The following table summarizes changes in Level 3 investments measured at fair value on a recurring basis.

(dollars in thousands)	2019			2018
Equity securities, beginning of period	$	53,728		$	168,809
Purchases	500			28,900
Sales	(9,448		)	(35,335		)
Net investment gains (losses) on Level 3 investments	1,212			(108,646		)
Transfers into Level 3	—			—
Transfers out of Level 3	—			—
Equity securities, end of period	$	45,992		$	53,728