Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 71,632	$ 46,231	$ 77,865
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	996	984	1,181
Net amortization of investments	10,787	14,015	16,247
Deferred income taxes	(1,462)	12,800	(2,249)
Net realized losses on investments	1,536	647	509
Net unrealized losses on equity securities	2,088
Net realized losses on disposal of assets		2	1
Share-based compensation	2,065	2,018	1,603
Changes in operating assets and liabilities:
Premiums receivable, net	11,756	8,771	2,359
Accrued interest receivable	438	725	325
Deferred policy acquisition costs	517	(951)	1,112
Amounts held by others	(7,855)	27,848	1,016
Other assets	1,873	(1,882)	1,631
Reserves for loss and loss adjustment expenses	26,564	29,069	24,743
Unearned premiums	(7,974)	(4,758)	(5,955)
Reinsurance balances	(21,873)	(6,495)	7,285
Amounts held for others and policyholder deposits	2,911	4,168	(17,066)
Accounts payable and other liabilities	4,269	(2,382)	3,605
Net cash provided by operating activities	98,268	130,810	114,212
Investing activities
Purchases of investments held-to-maturity	(99,330)	(222,104)	(102,830)
Purchases of investments available-for-sale	(124,128)	(108,517)	(216,466)
Purchases of equity securities	(11,459)	(8,503)
Purchases of short-term investments	(133,355)	(62,687)	(35,295)
Proceeds from maturities of investments held-to-maturity	99,984	152,995	177,159
Proceeds from sales and maturities of investments available-for-sale	100,357	112,179	115,552
Proceeds from sales of equity securities	3	1
Proceeds from sales and maturities of short-term investments	139,865	72,400	13,040
Proceeds from redemptions of other investments	130	13,172
Purchases of property and equipment	(1,126)	(478)	(1,638)
Net cash used in investing activities	(29,059)	(51,542)	(50,478)
Financing activities
Proceeds from stock option exercises	67		837
Tax benefit from share-based payments			995
Dividends to shareholders	(84,491)	(82,645)	(76,111)
Net cash used in financing activities	(84,424)	(82,645)	(74,279)
Change in cash and cash equivalents	(15,215)	(3,377)	(10,545)
Cash and cash equivalents at beginning of year	55,559	58,936	69,481
Cash and cash equivalents at end of year	40,344	55,559	58,936
Supplemental disclosure of cash flow information
Income taxes paid	$ 11,235	$ 28,255	$ 31,500