Schedule I - Financial Information of the Registrant (Parent Company) - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 330,609	$ 192,067
Receivables:
Notes - due from subsidiaries	2,464	2,987
Total receivables	72,003	71,462
Property and equipment, at cost:
Furniture and equipment	178,416	216,498
Accumulated depreciation	(151,483)	(182,663)
Total property and equipment, at cost	50,461	60,794
Investments in subsidiaries, on an equity-method basis	6,169	8,590
Operating lease assets	99,028
Goodwill	248,890	248,890	$ 231,428
Other assets	35,402	43,121
Total assets	1,592,785	1,372,930
Liabilities
Accounts payable and other liabilities	126,779	109,283
Operating lease liabilities	113,843
Notes payable	110,632	108,036
Total liabilities	839,026	693,093
Contingent liabilities and commitments
Stockholders’ equity
Common Stock – $1 par, authorized 51,500,000; issued 24,061,568 and 24,071,508; outstanding 23,709,407 and 23,719,347, respectively	24,062	24,072
Additional paid-in capital	164,217	162,642
Retained earnings	564,392	514,248
Accumulated other comprehensive (loss) income (AOCI):
Foreign currency translation adjustments	(13,027)	(19,505)
Net unrealized investment gains (losses)	10,328	(5,266)
Treasury stock – 352,161 common shares, at cost	(2,666)	(2,666)
Total stockholders’ equity	747,306	673,525
Total liabilities and stockholders' equity	1,592,785	1,372,930
Parent Company
Assets
Cash and cash equivalents	36,849	24,823
Receivables:
Notes - due from subsidiaries	5,193	6,609
Receivables from affiliates	260	7
Total receivables	5,453	6,616
Property and equipment, at cost:
Furniture and equipment	88	2,662
Accumulated depreciation	(83)	(2,449)
Total property and equipment, at cost	5	213
Investments in subsidiaries, on an equity-method basis	802,994	737,273
Operating lease assets	8,931
Goodwill	8,470	8,470
Other assets	15,810	17,469
Total assets	878,512	794,864
Liabilities
Accounts payable and other liabilities	21,417	22,464
Operating lease liabilities	10,914	0
Notes payable	98,875	98,875
Total liabilities	131,206	121,339
Contingent liabilities and commitments	0	0
Stockholders’ equity
Common Stock – $1 par, authorized 51,500,000; issued 24,061,568 and 24,071,508; outstanding 23,709,407 and 23,719,347, respectively	24,062	24,072
Additional paid-in capital	164,217	162,642
Retained earnings	564,392	514,248	$ 491,698	$ 471,788
Accumulated other comprehensive (loss) income (AOCI):
Foreign currency translation adjustments	(13,027)	(19,505)
Net unrealized investment gains (losses)	10,328	(5,266)
Treasury stock – 352,161 common shares, at cost	(2,666)	(2,666)
Total stockholders’ equity	747,306	673,525
Total liabilities and stockholders' equity	$ 878,512	$ 794,864