Differences in Tax Provision for Financial Statement Purposes and Expected Tax Provision at Weighted Average Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Expected tax provision at weighted average tax rate	$ (1,001)	$ (2,494)	$ 3,380	$ (5,527)
Adjustments:
Tax exempt interest	0	0	(1)	(5)
Dividend exclusion	(33)	(68)	(256)	(203)
Base Erosion Anti-Abuse Tax	0	(731)	0	0
Non-deductible interest	695	0	2,063	0
Other	22	1	(23)	(209)
Total income tax expense (benefit)	$ (317)	$ (3,292)	$ 5,163	$ (5,944)
Expected tax provision at weighted average tax rate, % of Pre-Tax Income	(15.60%)	(571.90%)	7.30%	(51.80%)
Adjustments:
Tax exempt interest, % of Pre-Tax Income	(0.00%)	(0.00%)	(0.00%)	(0.00%)
Dividend exclusion, % of Pre-Tax Income	(0.50%)	(15.60%)	(0.60%)	(1.90%)
Base Erosion Anti-Abuse Tax, % of Pre-Tax Income	0.00%	(167.70%)	0.00%	0.00%
Non-deductible interest, % of Pre-Tax Income	10.80%	0.00%	4.50%	0.00%
Other, % of Pre-Tax Income	0.30%	0.20%	0.00%	(2.00%)
Effective income tax expense (benefit), % of Pre-Tax Income	(5.00%)	(755.00%)	11.20%	(55.70%)