Summary of Liabilities for Variable Contract Guarantees (Detail) - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2017 |
Dec. 31, 2016 |
| Liabilities for Guarantees on Long-Duration Contracts [Line Items] |
|
|
| Beginning balance |
$ 166,427
|
$ 181,131
|
| Incurred guaranteed benefits |
(22,674)
|
(11,222)
|
| Paid guaranteed benefits |
(1,508)
|
(3,482)
|
| Ending balance |
142,245
|
166,427
|
| Guaranteed Minimum Death Benefit |
|
|
| Liabilities for Guarantees on Long-Duration Contracts [Line Items] |
|
|
| Beginning balance |
1,985
|
2,239
|
| Incurred guaranteed benefits |
260
|
528
|
| Paid guaranteed benefits |
(207)
|
(782)
|
| Ending balance |
2,038
|
1,985
|
| Guaranteed Minimum Income Benefit |
|
|
| Liabilities for Guarantees on Long-Duration Contracts [Line Items] |
|
|
| Beginning balance |
3,217
|
4,023
|
| Incurred guaranteed benefits |
(185)
|
(246)
|
| Paid guaranteed benefits |
(1,288)
|
(560)
|
| Ending balance |
1,744
|
3,217
|
| Guaranteed Minimum Accumulation Benefit |
|
|
| Liabilities for Guarantees on Long-Duration Contracts [Line Items] |
|
|
| Beginning balance |
16,594
|
27,579
|
| Incurred guaranteed benefits |
(6,063)
|
(8,845)
|
| Paid guaranteed benefits |
(13)
|
(2,140)
|
| Ending balance |
10,518
|
16,594
|
| Guaranteed Minimum Withdrawal Benefit |
|
|
| Liabilities for Guarantees on Long-Duration Contracts [Line Items] |
|
|
| Beginning balance |
144,631
|
147,290
|
| Incurred guaranteed benefits |
(16,686)
|
(2,659)
|
| Ending balance |
$ 127,945
|
$ 144,631
|