CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 72,988us-gaap_NetIncomeLoss	$ 58,977us-gaap_NetIncomeLoss	$ 30,312us-gaap_NetIncomeLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Bad debt expense	431us-gaap_ProvisionForDoubtfulAccounts	428us-gaap_ProvisionForDoubtfulAccounts	319us-gaap_ProvisionForDoubtfulAccounts
Depreciation and amortization	1,194us-gaap_DepreciationAndAmortization	1,012us-gaap_DepreciationAndAmortization	840us-gaap_DepreciationAndAmortization
Amortization of share-based compensation	12,342us-gaap_ShareBasedCompensation	6,417us-gaap_ShareBasedCompensation	3,830us-gaap_ShareBasedCompensation
Amortization of original issue discount on debt	840	601
Accretion of deferred credit	(840)us-gaap_AccretionExpense	(601)us-gaap_AccretionExpense
Book overdraft increase (decrease)	(9,023)	(11,047)	509
Net realized (gains) losses on investments	(5,627)	14,740	11,943
Net change in unrealized (gains) losses on investments		(7,850)	(9,443)
Net foreign currency (gains) losses on investments			(22)
Amortization of premium/accretion of discount, net	2,116	1,582	(4)
Deferred income taxes	1,118	7,363	3,813
Excess tax (benefits) shortfall from share-based compensation	(7,006)	(359)	1,760
Other	19us-gaap_OtherNoncashIncomeExpense	10us-gaap_OtherNoncashIncomeExpense	5us-gaap_OtherNoncashIncomeExpense
Net change in assets and liabilities relating to operating activities:
Restricted cash and cash equivalents	(35)	30,409	45,304
Prepaid reinsurance premiums	50,709	(1,293)	3,174
Reinsurance recoverable	52,660	(18,656)	(3,485)
Reinsurance receivable, net	(7,265)	24,131	30,871
Premiums receivable, net	(4,911)	3,256	(4,589)
Accrued investment income	(230)	(720)	325
Other receivables	12	131	360
Deferred policy acquisition costs, net	(9,761)	1,383	(4,286)
Purchase of trading securities		(26,009)	(343,962)
Proceeds from sales of trading securities		102,661	360,000
Income taxes recoverable	2,477	(5,558)	(2,594)
Other assets	(740)	(459)	331
Unpaid losses and loss adjustment expenses	(24,869)	(34,019)	6,026
Unearned premiums	12,260	(4,583)	28,229
Advance premium	(5,040)	7,937	(4,368)
Accounts payable	680	(927)	54
Reinsurance payable, net	(20,166)	973	(2,237)
Income taxes payable	6,239	2,226	(13,801)
Other liabilities and accrued expenses	2,774	4,803	3,292
Net cash provided by (used in) operating activities	123,346	156,959	142,506
Cash flows from investing activities:
Proceeds from sale of property and equipment	84	8	28
Purchase of property and equipment	(9,267)	(1,350)	(2,726)
Purchases of equity securities, available for sale	(116,541)	(77,859)
Purchases of fixed maturities, available for sale	(106,885)	(305,330)
Purchases of short-term investments, available for sale	(50,000)
Proceeds from sales of equity securities, available for sale	163,981	15,542
Proceeds from sales of fixed maturities, available for sale	17,153
Maturities of fixed maturities, available for sale	24,287	16,306
Net cash provided by (used in) investing activities	(77,188)	(352,683)	(2,698)
Cash flows from financing activities:
Preferred stock dividend	(13)	(29)	(287)
Common stock dividend	(19,240)us-gaap_PaymentsOfDividendsCommonStock	(17,725)us-gaap_PaymentsOfDividendsCommonStock	(18,669)us-gaap_PaymentsOfDividendsCommonStock
Issuance of common stock	73		207
Purchase of treasury stock	(29,736)	(32,366)
Proceeds received from issuance of common and contingently redeemable common stock	19,000
Payments related to tax withholding for share-based compensation	(17,655)	(3,161)	(121)
Excess tax benefits (shortfall) from share-based compensation	7,006	359	(1,760)
Repayment of debt	(7,471)us-gaap_RepaymentsOfDebt	(1,471)us-gaap_RepaymentsOfDebt	(1,471)us-gaap_RepaymentsOfDebt
Proceeds from borrowings		20,000
Net cash provided by (used in) financing activities	(48,036)	(34,393)	(22,101)
Net increase (decrease) in cash and cash equivalents	(1,878)	(230,117)	117,707
Cash and cash equivalents at beginning of period	117,275	347,392	229,685
Cash and cash equivalents at end of period	115,397	117,275	347,392
Supplemental cash and non-cash flow disclosures:
Interest paid	1,486us-gaap_InterestPaid	1,166us-gaap_InterestPaid	414us-gaap_InterestPaid
Income taxes paid	44,769us-gaap_IncomeTaxesPaidNet	36,634us-gaap_IncomeTaxesPaidNet	28,151us-gaap_IncomeTaxesPaidNet
Non-cash transfer of investments from trading to available for sale portfolio		$ 4,004us-gaap_TransferToInvestments

The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method.

Name:	us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration