Differences in Tax Provision for Financial Statement Purposes and Expected Tax Provision at Weighted Average Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax [Line Items]
Expected tax provision at weighted average rate	$ (2,364)	$ (4,852)
Adjustments:
Tax exempt interest	(84)	(104)
Dividend exclusion	(193)	(239)
Other	(361)	23
Actual tax on continuing operations	$ (3,002)	$ (5,172)
Expected tax provision at weighted average rate	(25.50%)	(248.50%)
Adjustments:
Tax exempt interest, % of Pre-Tax Income	(0.90%)	(5.30%)
Dividend exclusion, % of Pre-Tax Income	(2.10%)	(12.20%)
Other, % of Pre-Tax Income	(3.80%)	1.20%
Actual tax on continuing operations, % of Pre-Tax Income	(32.30%)	(264.80%)