Summary of Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares	Sep. 30, 2016 USD ($) $ / shares	Jun. 30, 2016 USD ($) $ / shares	Mar. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Sep. 30, 2015 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares	Mar. 31, 2015 USD ($) $ / shares	Dec. 31, 2016 USD ($) segment $ / shares shares	Dec. 31, 2015 USD ($) segment $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares
Investments
Maximum period considered for applying equity method accounting based on financial information provided by the investee									3 months
Accounts Receivable
Premiums receivable, allowance for doubtful accounts | $	$ 435				$ 425				$ 435	$ 425
Deferred Policy Acquisition Costs
Amortization expense | $									141,540	138,239	$ 132,526
Marketing and Advertising Expense [Abstract]
Advertising costs | $									2,063	1,906	2,108
Earnings per Weighted Average Common Share
Net income (loss) available to common shareholders for basic and diluted earnings per share | $	$ 11,953	$ 18,597	$ 21,365	$ 12,670	$ 10,290	$ 11,981	$ (1,053)	$ (35,071)	64,585	(13,853)	59,354
Allocation of income for participating shares | $									(436)		(567)
Net income (loss) from continuing operations attributed to common shareholders | $									$ 64,149	$ (13,853)	$ 58,787
Total weighted average common shares outstanding, including participating shares									15,048,048	14,985,475	15,107,339
Less: weighted average participating shares									(101,595)	(118,868)	(144,292)
Total weighted average common shares outstanding									14,946,453	14,866,607	14,963,047
Common equivalent shares- stock options									134		2,391
Common equivalent shares- non-vested performance stock grants									85,676		87,307
Diluted earnings per share denominator									15,032,263	14,866,607	15,052,745
Basic earnings (loss) per share (in dollars per share) | $ / shares	$ 0.79	$ 1.24	$ 1.42	$ 0.84	$ 0.69	$ 0.80	$ (0.07)	$ (2.37)	$ 4.29	$ (0.93)	$ 3.93
Diluted earnings (loss) per share (in dollars per share) | $ / shares	0.79	1.23	1.41	0.84	0.69	0.80	(0.07)	(2.37)	$ 4.27	$ (0.93)	$ 3.91
Antidilutive common shares									0	1,587	0
Antidilutive common shares under non performance stock grants									0	46,805	0
Undistributed Earnings, Diluted [Abstract]
Basic earnings (loss) per share (in dollars per share) | $ / shares	0.79	1.24	1.42	0.84	0.69	0.80	(0.07)	(2.37)	$ 4.29	$ (0.93)	$ 3.93
Dividends declared | $ / shares									(2.8)	(2.8)	(2.6)
Undistributed earnings (loss) | $ / shares									1.49	(3.73)	1.33
Diluted earnings (loss) per share (in dollars per share) | $ / shares	$ 0.79	$ 1.23	$ 1.41	$ 0.84	$ 0.69	$ 0.80	$ (0.07)	$ (2.37)	4.27	(0.93)	3.91
Undistributed earnings (loss) - Diluted | $ / shares									$ 1.47	$ (3.73)	$ 1.31
Premiums and Unearned Premiums
Term over which premiums are earned									1 year
Deferred revenue | $	$ 14,643				$ 14,712				$ 14,643	$ 14,712
Segments
Number of business segments | segment									1	1
Previously Reported
Earnings per Weighted Average Common Share
Total weighted average common shares outstanding											15,107,339
Diluted earnings per share denominator											15,197,036
Minimum
Equipment and Leasehold Improvements
Estimated useful lives									3 years
Maximum
Equipment and Leasehold Improvements
Estimated useful lives									10 years
Accounting Standards Update 2015-07
Segments
Alternative investments fair value | $	$ 19,961				$ 19,097				$ 19,961	$ 19,097