Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating activities
Net income	$ 29,353	$ 24,181	$ 34,520
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	1,112	1,015	1,028
Net amortization/accretion of investments	10,151	6,660	4,989
Deferred income taxes	115	(1,525)	(2,169)
Net realized gains on investments	(2,979)	(2,228)	(2,449)
Loss/(gain) on sale of asset	1	32	(16)
Share-based compensation	641	471	2,325
Changes in operating assets and liabilities:
Premiums receivable	(20,727)	1,395	28,952
Accrued interest receivable	(872)	(1,816)	(539)
Deferred policy acquisition costs	(1,841)	(1,441)	859
Other assets	445	(2,008)	(9,268)
Reserve for loss and loss adjustment expenses	32,236	6,010	(2,451)
Unearned premiums	21,829	7,205	(11,006)
Reinsurance balances	(5,910)	140	(13,248)
Amounts held for others and policyholder deposits	12,912	5,355	6,082
Accounts payable and other liabilities	4,582	263	7,235
Net cash provided by operating activities	81,048	43,709	44,844
Investing activities
Purchases of investments held-to-maturity	(79,042)	(86,669)	(68,095)
Purchases of investments available-for-sale	(92,751)	(120,637)	(36,936)
Purchases of short-term investments	(95,954)	(87,460)	(89,427)
Proceeds from maturities of investments held-to-maturity	134,994	97,863	66,021
Proceeds from sales and maturities of investments available-for-sale	52,514	36,329	30,157
Proceeds from sales and maturities of short-term investments	72,105	118,759	64,813
Purchases of property and equipment	(1,196)	(1,128)	(3,206)
Proceeds from sales of property and equipment			16
Net cash used in investing activities	(9,330)	(42,943)	(36,657)
Financing activities
Proceeds from stock option exercise	781	3,339	1,455
Tax benefit from share-based payments	421	1,043	238
Purchase of treasury stock		(10,268)	(12,102)
Redemption of subordinated debt securities	(25,780)	(10,310)
Net cash used in financing activities	(24,578)	(16,196)	(10,409)
Change in cash and cash equivalents	47,140	(15,430)	(2,222)
Cash and cash equivalents at beginning of year	45,536	60,966	63,188
Cash and cash equivalents at end of year	92,676	45,536	60,966
Supplemental disclosure of cash flow information
Interest paid	686	1,412	1,547
Income taxes paid	$ 7,004	$ 1,000	$ 6,256