CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$ 22,330us-gaap_NetIncomeLoss	$ 13,549us-gaap_NetIncomeLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Bad debt expense	141us-gaap_ProvisionForDoubtfulAccounts	71us-gaap_ProvisionForDoubtfulAccounts
Depreciation and amortization	389us-gaap_DepreciationAndAmortization	280us-gaap_DepreciationAndAmortization
Amortization of share-based compensation	2,752us-gaap_ShareBasedCompensation	1,685us-gaap_ShareBasedCompensation
Amortization of original issue discount on debt	181	250
Accretion of deferred credit	(181)us-gaap_AccretionExpense	(250)us-gaap_AccretionExpense
Book overdraft increase (decrease)	1,554	(11,962)
Net realized (gains) losses on investments	(171)	(902)
Amortization of premium/accretion of discount, net	430	499
Deferred income taxes	(620)	509
Excess tax (benefits) shortfall from share-based compensation	(4,136)	(6,342)
Other	61us-gaap_OtherNoncashIncomeExpense	(12)us-gaap_OtherNoncashIncomeExpense
Net change in assets and liabilities relating to operating activities:
Restricted cash and cash equivalents		(35)
Prepaid reinsurance premiums	(4,186)	5,188
Reinsurance recoverable	3,821	31,750
Reinsurance receivable, net	3,171	(6,801)
Premiums receivable, net	(4,187)	(1,715)
Accrued investment income	(90)	(32)
Other receivables	(425)	(636)
Income taxes recoverable	5,675	1,953
Deferred policy acquisition costs, net	(535)	6
Other assets	751	350
Unpaid losses and loss adjustment expenses	(9,192)	(8,665)
Unearned premiums	14,935	1,273
Accounts payable	(1,649)	1,058
Reinsurance payable, net	25,192	7,422
Income taxes payable	9,018	4,691
Other liabilities and accrued expenses	(8,633)	(5,779)
Advance premium	4,266	2,454
Net cash provided by (used in) operating activities	60,662	29,857
Cash flows from investing activities:
Proceeds from sale of property and equipment	50	17
Purchases of property and equipment	(7,613)	(751)
Payments to acquire a business	(1,000)
Purchases of equity securities	(17,056)	(4,782)
Purchases of fixed maturities	(24,965)	(20,475)
Proceeds from sales of equity securities	15,300	10,071
Proceeds from sales of fixed maturities	12,891	4,370
Maturities of fixed maturities	19,786	7,528
Maturities of short-term investments	12,500
Net cash provided by (used in) investing activities	9,893	(4,022)
Cash flows from financing activities:
Preferred stock dividend	(2)	(5)
Common stock dividend	(4,237)us-gaap_PaymentsOfDividendsCommonStock	(3,463)us-gaap_PaymentsOfDividendsCommonStock
Issuance of common stock	503
Purchase of treasury stock		(14,737)
Payments related to tax withholding for share-based compensation	(3,673)	(8,108)
Excess tax benefits (shortfall) from share-based compensation	4,136	6,342
Repayment of debt	(368)us-gaap_RepaymentsOfDebt	(368)us-gaap_RepaymentsOfDebt
Net cash provided by (used in) financing activities	(3,641)	(20,339)
Net increase (decrease) in cash and cash equivalents	66,914	5,496
Cash and cash equivalents at beginning of period	115,397	117,275
Cash and cash equivalents at end of period	182,311	122,771
Supplemental cash and non-cash flow disclosures:
Interest paid	310us-gaap_InterestPaid	433us-gaap_InterestPaid
Income taxes paid	$ 1,619us-gaap_IncomeTaxesPaidNet	$ 2,404us-gaap_IncomeTaxesPaidNet

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