Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 29,021,000	$ 65,861,000	$ 62,664,000
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	4,198,000	5,212,000	8,110,000
Net amortization of discounts and premiums on investments in fixed-maturity securities	726,000	855,000	782,000
Depreciation and amortization	5,408,000	5,251,000	4,958,000
Deferred income tax expense (benefit)	155,000	(1,101,000)	(4,742,000)
Net realized investment (gains) losses	(2,601,000)	608,000	(4,735,000)
Other-than-temporary impairment losses	2,482,000	4,681,000	107,000
Income from real estate investment under acquisition, development and construction arrangement		(344,000)	(85,000)
Gain on repurchases of convertible senior notes	(153,000)
Gain on bargain purchase	(2,071,000)
Gain on remeasurement of previously held investment	(4,005,000)
Impairment loss	388,000
Loss from unconsolidated joint venture		125,000	23,000
Net (income) loss from limited partnership interests	(1,207,000)	3,244,000	90,000
Distributions received from limited partnership interests	544,000	12,000	0
Foreign currency remeasurement loss	29,000	66,000	29,000
Other	18,000	26,000	(1,000)
Changes in operating assets and liabilities:
Accrued interest and dividends receivable	(300,000)	(331,000)	74,000
Income taxes	(1,192,000)	766,000	(3,167,000)
Premiums receivable	2,355,000	(3,807,000)	(1,150,000)
Prepaid reinsurance premiums	16,193,000	(6,651,000)	(6,030,000)
Deferred policy acquisition costs	1,963,000	(3,588,000)	(943,000)
Other assets	29,054,000	(7,230,000)	(20,086,000)
Losses and loss adjustment expenses	18,802,000	2,782,000	5,222,000
Unearned premiums	(11,487,000)	(26,781,000)	42,164,000
Advance premiums	(332,000)	603,000	(124,000)
Assumed reinsurance balances payable	2,210,000	866,000	(4,442,000)
Accrued expenses and other liabilities	(2,223,000)	4,157,000	10,011,000
Net cash provided by operating activities	87,975,000	45,282,000	88,729,000
Cash flows from investing activities:
Investment in real estate under acquisition, development, and construction arrangement		(6,968,000)	(2,803,000)
Acquisition of real estate business, net of cash acquired	(11,651,000)
Investments in limited partnership interests	(4,670,000)	(24,636,000)	(2,640,000)
Investment in unconsolidated joint venture	(90,000)	(435,000)	(4,500,000)
Purchase of property and equipment	(865,000)	(840,000)	(453,000)
Purchase of real estate investments	(2,261,000)	(4,871,000)	(413,000)
Purchase of fixed-maturity securities	(85,530,000)	(98,501,000)	(83,365,000)
Purchase of equity securities	(22,434,000)	(32,878,000)	(44,257,000)
Proceeds from investment in real estate under acquisition, development and construction arrangement	10,200,000
Proceeds from sales of fixed-maturity securities	40,454,000	53,711,000	98,365,000
Proceeds from calls, repayments and maturities of fixed-maturity securities	4,692,000	9,344,000	4,603,000
Proceeds from sales of equity securities	23,127,000	25,695,000	16,810,000
Proceeds from sales of real estate investments		5,000	1,000
Net cash used in investing activities	(49,028,000)	(80,374,000)	(18,652,000)
Cash flows from financing activities:
Net borrowing under revolving credit facility	1,238,000
Proceeds from the exercise of common stock options	150,000	263,000	125,000
Cash dividends paid	(12,438,000)	(12,428,000)	(12,355,000)
Cash dividends received under share repurchase forward contract	747,000	747,000	685,000
Proceeds from the issuance of long-term debt	18,200,000
Repurchases of convertible senior notes	(11,347,000)
Repayment of debt	(455,000)
Repurchases of common stock	(464,000)	(792,000)	(643,000)
Repurchases of common stock under share repurchase plan	(20,026,000)	(1,610,000)	(38,354,000)
Redemption of Series A preferred stock			(34,000)
Purchase of non-controlling interest	(2,064,000)
Debt issuance costs	(339,000)		(234,000)
Tax benefits on stock-based compensation	641,000	2,295,000	2,080,000
Net cash used in financing activities	(26,157,000)	(11,525,000)	(48,730,000)
Effect of exchange rate changes on cash	3,000	(61,000)	(29,000)
Net increase (decrease) in cash and cash equivalents	12,793,000	(46,678,000)	21,318,000
Cash and cash equivalents at beginning of year	267,738,000	314,416,000	293,098,000
Cash and cash equivalents at end of year	280,531,000	267,738,000	314,416,000
Supplemental disclosure of cash flow information:
Cash paid for income taxes	18,857,000	38,371,000	43,902,000
Cash paid for interest	7,222,000	7,211,000	6,258,000
Non-cash investing and financing activities:
Unrealized gain (loss) on investments in available-for-sale securities, net of tax	4,434,000	(2,457,000)	(448,000)
Details of business acquisition:
Fair value of assets acquired	32,569,000
Less:Purchase price	(14,514,000)
Carrying value of previously held interest	(2,859,000)
Gain on remeasurement of previously held interest	(4,005,000)
Gain on bargain purchase	(2,071,000)
Liabilities assumed	9,120,000
Receivable from sales of available-for-sale securities	350,000		34,000
Payable on purchases of available-for-sale securities	$ 50,000	$ 1,000	1,908,000
Series A Preferred Stock [Member]
Non-cash investing and financing activities:
Conversion of Series A preferred stock to common stock			$ 972,000