Business Segment's Contribution to Select Statements of Income (Loss) Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Policy charge revenue	$ 37,476	$ 37,039
Net investment income	27,944	26,452
Net realized investment gains (losses)	31	(134)
Derivative gains (losses)	(24,228)	3,371
Total Revenues	41,223	66,728
Interest credited to policyholder liabilities	12,983	14,030
Policy benefits (net of reinsurance recoveries)	(9,490)	43,054
Amortization (accretion) of DAC	1,132	942
Amortization (accretion) of VOBA	2,364	5,380
Insurance, general and administrative expenses	8,843	9,926
Total Benefits and Expenses	15,832	73,332
Income (Loss) Before Taxes	25,391	(6,604)
Income Tax Expense (Benefit)	575	0
Net Income (Loss)	24,816	(6,604)
Operating Segments | Annuity
Segment Reporting Information [Line Items]
Policy charge revenue	24,011	23,722
Net investment income	14,230	12,018
Net realized investment gains (losses)	(198)	(222)
Derivative gains (losses)	(24,228)	3,355
Total Revenues	13,815	38,873
Interest credited to policyholder liabilities	1,686	2,172
Policy benefits (net of reinsurance recoveries)	(16,121)	28,653
Amortization (accretion) of DAC	1,132	942
Amortization (accretion) of VOBA	1,623	1,733
Insurance, general and administrative expenses	8,123	9,157
Total Benefits and Expenses		42,657
Income (Loss) Before Taxes	17,372	(3,784)
Income Tax Expense (Benefit)	393	1,277
Net Income (Loss)	16,979	(5,061)
Operating Segments | Life Insurance
Segment Reporting Information [Line Items]
Policy charge revenue	13,465	13,317
Net investment income	13,714	14,434
Net realized investment gains (losses)	229	88
Derivative gains (losses)	0	16
Total Revenues	27,408	27,855
Interest credited to policyholder liabilities	11,297	11,858
Policy benefits (net of reinsurance recoveries)	6,631	14,401
Amortization (accretion) of DAC	0	0
Amortization (accretion) of VOBA	741	3,647
Insurance, general and administrative expenses	720	769
Total Benefits and Expenses	19,389	30,675
Income (Loss) Before Taxes	8,019	(2,820)
Income Tax Expense (Benefit)	182	(1,277)
Net Income (Loss)	7,837	$ (1,543)
Intersegment Eliminations | Annuity
Segment Reporting Information [Line Items]
Total Benefits and Expenses	$ (3,557)