Fair Value of Financial Instruments - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	$ 2,357,154	$ 2,356,996
Equity securities	33,689	40,684
Separate account assets	2,377,654	2,485,745
Separate account liabilities	$ 2,377,654	2,485,745
Fair value assumptions, percentage of securities assessed by third-party pricing service	95.00%
Fair Value, Recurring Measurements [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale securities	$ 2,357,154	2,356,996
Equity securities	33,689	40,684
Trading securities	22,399	43,233
Separate account assets	2,377,654	2,485,745
Assets, fair value disclosure	4,790,896	4,926,658
Separate account liabilities	2,377,654	2,485,745
Liabilities, fair value disclosure	2,377,654	2,485,745
Fair Value, Recurring Measurements [Member] \| Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale securities	5,251	5,865
Equity securities	32,533	39,499
Assets, fair value disclosure	37,784	45,364
Fair Value, Recurring Measurements [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale securities	2,346,761	2,350,681
Equity securities	1,030	1,050
Trading securities	22,399	43,233
Separate account assets	2,377,654	2,485,745
Assets, fair value disclosure	4,747,844	4,880,709
Separate account liabilities	2,377,654	2,485,745
Liabilities, fair value disclosure	2,377,654	2,485,745
Fair Value, Recurring Measurements [Member] \| Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale securities	5,142	450
Equity securities	126	135
Assets, fair value disclosure	5,268	585
Fair Value, Recurring Measurements [Member] \| U.S. Government and Agencies [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	10,151	10,484
Fair Value, Recurring Measurements [Member] \| U.S. Government and Agencies [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	10,151	10,484
Fair Value, Recurring Measurements [Member] \| Foreign Government [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	170,068	161,072
Fair Value, Recurring Measurements [Member] \| Foreign Government [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	170,068	161,072
Fair Value, Recurring Measurements [Member] \| States and Political Subdivisions [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	126,754	122,593
Fair Value, Recurring Measurements [Member] \| States and Political Subdivisions [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	126,754	122,593
Fair Value, Recurring Measurements [Member] \| Corporates [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	1,515,887	1,499,651
Fair Value, Recurring Measurements [Member] \| Corporates [Member] \| Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	5,251	5,865
Fair Value, Recurring Measurements [Member] \| Corporates [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	1,505,601	1,493,786
Fair Value, Recurring Measurements [Member] \| Corporates [Member] \| Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	5,035
Fair Value, Recurring Measurements [Member] \| Residential Mortgage-backed Securities [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	317,357	312,523
Fair Value, Recurring Measurements [Member] \| Residential Mortgage-backed Securities [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	317,330	312,497
Fair Value, Recurring Measurements [Member] \| Residential Mortgage-backed Securities [Member] \| Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	27	26
Fair Value, Recurring Measurements [Member] \| Commercial Mortgage-backed Securities [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	122,044	132,005
Fair Value, Recurring Measurements [Member] \| Commercial Mortgage-backed Securities [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	122,044	132,005
Fair Value, Recurring Measurements [Member] \| Other Asset-backed Securities [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	94,893	118,668
Fair Value, Recurring Measurements [Member] \| Other Asset-backed Securities [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	94,813	118,244
Fair Value, Recurring Measurements [Member] \| Other Asset-backed Securities [Member] \| Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total available-for-sale fixed-maturity securities	$ 80	$ 424

Fair value assumptions percentage of securities assessed by third party pricing service.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value of financial and nonfinancial obligations.

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Amount of asset at fair value held for benefit of separate account policyholder.

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Amount of liability for variable contract in which all or portion of contract holder's funds is allocated to specific separate account and supported by assets held in separate account.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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