Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 320,087	$ (5,728)	$ 144,877
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	64,730	58,791	55,343
Net realized investment (gains) losses	(222,793)	133,520	(83,650)
Increase in premiums receivable	(49,832)	(80,979)	(14,908)
Decrease (increase) in reinsurance recoverables	142,314	(164,739)	(43,043)
Gain on sale of fixed assets	0	0	(3,078)
Changes in current and deferred income taxes	72,545	(13,898)	(3,010)
(Increase) decrease in deferred policy acquisition costs	(18,035)	(16,980)	2,675
Increase in loss and loss adjustment expense reserves	91,843	318,799	220,365
Increase in unearned premiums	119,366	134,254	27,490
Increase (decrease) in accounts payable and accrued expenses	26,493	6,586	(4,178)
Share-based compensation	123	145	60
Other, net	(27,163)	13,663	42,462
Net cash provided by operating activities	519,678	383,434	341,405
Fixed maturity securities available for sale in nature:
Purchases	(491,795)	(706,224)	(734,397)
Sales	136,560	189,306	100,709
Calls or maturities	316,860	334,626	575,735
Equity securities available for sale in nature
Purchases	(1,174,759)	(1,026,827)	(831,310)
Sales	1,088,701	954,755	679,571
Calls	0	0	7,100
Changes in securities payable and receivable	(2,536)	4,035	(44,740)
(Increase) decrease in short-term investments	(240,391)	45,747	73,005
Purchase of fixed assets	(40,088)	(27,959)	(19,443)
Sale of fixed assets	0	0	6,239
Other, net	6,247	10,105	1,934
Net cash used in investing activities	(401,201)	(222,436)	(185,597)
CASH FLOWS FROM FINANCING ACTIVITIES
Dividends paid to shareholders	(139,071)	(138,478)	(137,886)
Proceeds from stock options exercised	701	358	2,162
Net proceeds from issuance of senior notes	0	0	371,011
Payoff of principal on loan and credit facilities	0	0	(320,000)
Net cash used in financing activities	(138,370)	(138,120)	(84,713)
Net (decrease) increase in cash	(19,893)	22,878	71,095
Cash:
Beginning of year	314,291	291,413	220,318
End of year	294,398	314,291	291,413
SUPPLEMENTAL CASH FLOW DISCLOSURE
Interest paid	16,586	16,586	9,863
Income taxes (refunded) paid, net	$ (14,564)	$ (10,989)	$ 25,218