Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net income	$ 92,690	$ 71,632	$ 46,231
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	942	996	984
Net amortization of investments	8,659	10,787	14,015
Deferred income taxes	872	(1,462)	12,800
Net realized losses on investments	80	1,536	647
Net unrealized (gains) losses on equity securities	(4,758)	2,088
Net realized losses on disposal of assets	3		2
Share-based compensation	2,351	2,065	2,018
Changes in operating assets and liabilities:
Premiums receivable, net	4,525	11,756	8,771
Accrued interest receivable	467	438	725
Deferred policy acquisition costs	686	517	(951)
Amounts held by others		(7,855)	27,848
Other assets	710	1,873	(1,882)
Reserves for loss and loss adjustment expenses	(25,522)	26,564	29,069
Unearned premiums	(8,423)	(7,974)	(4,758)
Reinsurance balances	16,093	(21,873)	(6,495)
Amounts held for others and policyholder deposits	(5,528)	2,911	4,168
Accounts payable and other liabilities	(5,023)	4,269	(2,382)
Net cash provided by operating activities	78,824	98,268	130,810
Investing activities
Purchases of investments held-to-maturity	(152,133)	(99,330)	(222,104)
Purchases of investments available-for-sale	(63,513)	(124,128)	(108,517)
Purchases of equity securities	(4,495)	(11,459)	(8,503)
Purchases of short-term investments	(125,763)	(133,355)	(62,687)
Proceeds from maturities of investments held-to-maturity	159,702	99,984	152,995
Proceeds from sales and maturities of investments available-for-sale	114,869	100,357	112,179
Proceeds from sales of equity securities		3	1
Proceeds from sales and maturities of short-term investments	84,039	139,865	72,400
Proceeds from redemptions of other investments		130	13,172
Purchases of property and equipment	(1,018)	(1,126)	(478)
Net cash provided by (used in) investing activities	11,688	(29,059)	(51,542)
Financing activities
Proceeds from stock option exercises	20	67
Finance lease purchases	(47)
Dividends to shareholders	(87,016)	(84,491)	(82,645)
Net cash used in financing activities	(87,043)	(84,424)	(82,645)
Change in cash and cash equivalents	3,469	(15,215)	(3,377)
Cash and cash equivalents at beginning of year	40,344	55,559	58,936
Cash and cash equivalents at end of year	43,813	40,344	55,559
Supplemental disclosure of cash flow information
Income taxes paid	$ 20,850	$ 11,235	$ 28,255