SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
ASSETS
Cash	$ 39,469	$ 44,314	$ 81,184
Short-term investments, at cost which approximates fair value	23,232	30,462
Investments in unconsolidated investee, at equity value	49,793	52,128
Fixed income:
Available-for-sale, at fair value (amortized cost - $18,839 in 2013 and $19,967 in 2012 )	1,440,052	1,378,582
Property and equipment, at cost, net of accumulated depreciation of $312 in 2013 and $240 in 2012	40,261	27,987
Total assets	2,740,310	2,644,632
Liabilities:
Total liabilities	1,911,344	1,848,269
Shareholders' equity:
Common stock ($1 par value, authorized 100,000,000 shares, issued 65,912,638 shares in 2013 and 65,455,462 shares in 2012, and outstanding 42,982,424 shares in 2013 and 42,525,248 shares in 2012)	65,913	65,455
Paid in capital	208,705	202,535
Accumulated other comprehensive earnings, net of tax	136,027	143,170
Retained earnings	811,320	778,202
Deferred compensation	11,562	11,106
Treasury shares at cost (22,930,214 shares in 2013 and 2012)	(404,561)	(404,105)
Total shareholders' equity	828,966	796,363	792,634	769,151
Total liabilities and shareholders' equity	2,740,310	2,644,632
Debt, notes payable due 2023
Liabilities:
Notes payable	149,582
Debt, notes payable due 2014
Liabilities:
Notes payable		100,000
PARENT COMPANY
ASSETS
Cash	181	14,023	346	26
Short-term investments, at cost which approximates fair value	13,394	431
Accounts receivable, affiliates	2,350	3,699
Investments in subsidiaries, at equity value	905,620	822,856
Investments in unconsolidated investee, at equity value	49,793	52,128
Fixed income:
Available-for-sale, at fair value (amortized cost - $18,839 in 2013 and $19,967 in 2012 )	18,447	20,599
Property and equipment, at cost, net of accumulated depreciation of $312 in 2013 and $240 in 2012	3,446	709
Income taxes receivable - current	493
Deferred debt costs	1,398	112
Other assets	190	397
Total assets	995,312	914,954
Liabilities:
Income taxes payable--current		207
Income taxes payable--deferred	14,485	15,183
Interest payable, long-term debt	1,808	2,727
Other liabilities	471	474
Total liabilities	166,346	118,591
Shareholders' equity:
Common stock ($1 par value, authorized 100,000,000 shares, issued 65,912,638 shares in 2013 and 65,455,462 shares in 2012, and outstanding 42,982,424 shares in 2013 and 42,525,248 shares in 2012)	65,913	65,455
Paid in capital	208,705	202,535
Accumulated other comprehensive earnings, net of tax	136,027	143,170
Retained earnings	811,320	778,202
Deferred compensation	11,562	11,106
Treasury shares at cost (22,930,214 shares in 2013 and 2012)	(404,561)	(404,105)
Total shareholders' equity	828,966	796,363
Total liabilities and shareholders' equity	995,312	914,954
PARENT COMPANY | Debt, notes payable due 2023
Liabilities:
Notes payable	149,582
PARENT COMPANY | Debt, notes payable due 2014
Liabilities:
Notes payable		$ 100,000