Tax Effects of Temporary Differences That Give Rise to Significant Portions of Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Deferred tax assets:
Discounted unpaid losses and loss adjustment expenses	$ 8,739	$ 7,492
Unearned premiums	8,117	3,409
Alternative minimum tax credit carryover	10,587	10,473
Net operating loss carryforward	6,264	0
Partnership K1 basis differences	245	145
Capital gain on derivative instruments	6,483	4,786
Investment impairments	2,709	379
Stock options	2,578	2,048
Deferred acquisition costs	149	187
Stat-to-GAAP reinsurance reserve	1,364	1,424
Intercompany transfers	1,738	1,919
Depreciation and amortization	93	(16)
Other	4,115	3,050
Total deferred tax assets	53,181	35,312
Deferred tax liabilities:
PGAAP adjustment for American Reliable	6,095
Intangible assets	4,615	3,220
Unrealized gain on securities available-for-sale and investments in limited partnerships included in accumulated other comprehensive income	4,827	10,263
Investment basis differences	1,066	692
Depreciation and amortization	(93)	16
Other	769	871
Total deferred tax liabilities	17,372	15,062
Total net deferred tax assets	$ 35,809	$ 20,250