Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities
Net income	$ 45,582	$ 58,792
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	760	884
Net amortization of investments	10,815	12,306
Deferred income taxes	342	(532)
Net realized (gains) losses on investments	761	(959)
Net realized losses on disposal of assets	2	1
Share-based compensation	1,283	1,143
Changes in operating assets and liabilities:
Premiums receivable, net	(2,492)	(15,623)
Accrued interest receivable	125	(263)
Deferred policy acquisition costs	(1,606)	49
Amounts held by others	27,848	1,016
Other assets	(5,131)	(2,929)
Reserves for loss and loss adjustment expenses	12,250	18,243
Unearned premiums	3,792	7,790
Reinsurance balances	(1,320)	(11,892)
Amounts held for others and policyholder deposits	2,503	6,557
Accounts payable and other liabilities	6,813	8,285
Net cash provided by operating activities	102,327	82,868
Investing activities
Purchases of investments held-to-maturity	(149,981)	(102,830)
Purchases of investments available-for-sale	(86,615)	(161,482)
Purchases of short-term investments	(53,789)	(12,132)
Proceeds from maturities of investments held-to-maturity	112,715	136,896
Proceeds from sales and maturities of investments available-for-sale	82,270	75,470
Proceeds from sales and maturities of short-term investments	17,610	8,033
Proceeds from redemptions of other investments	9,000
Purchases of property and equipment	(446)	(1,091)
Net cash used in investing activities	(69,236)	(57,136)
Financing activities
Proceeds from stock option exercises		837
Tax benefit from share-based payments		976
Dividends to shareholders	(11,649)	(10,414)
Net cash used in financing activities	(11,649)	(8,601)
Change in cash and cash equivalents	21,442	17,131
Cash and cash equivalents at beginning of period	58,936	69,481
Cash and cash equivalents at end of period	$ 80,378	$ 86,612