Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	$ 6,840	$ 6,576	$ 7,305	$ 6,622
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	7,187	7,206	7,187	7,206
Total gains (losses) (realized/unrealized):
Included in earnings	347	630	(118)	584
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	348	630	(118)	584
Equity securities \| Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Equity securities \| Other income
Total gains (losses) (realized/unrealized):
Included in earnings	347	630	(118)	584
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	348	630	(118)	584
Equity securities \| Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Equity securities \| Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Reinsurance recoverables
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1,868,539	571,117	760,558	488,825
Purchases	26,767	23,526	53,085	46,028
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	1,741,924	757,236	1,741,924	757,236
Total gains (losses) (realized/unrealized):
Included in earnings	(153,382)	162,593	928,281	222,383
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(141,848)	167,330	940,465	229,926
Reinsurance recoverables \| Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(153,382)	162,593	928,281	222,383
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(141,848)	167,330	940,465	229,926
Reinsurance recoverables \| Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Reinsurance recoverables \| Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Reinsurance recoverables \| Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Future policy benefits
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(1,868,539)	(571,117)	(760,558)	(488,825)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	(26,767)	(23,526)	(53,085)	(46,028)
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(1,741,924)	(757,236)	(1,741,924)	(757,236)
Total gains (losses) (realized/unrealized):
Included in earnings	153,382	(162,593)	(928,281)	(222,383)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	141,848	(167,330)	(940,465)	(229,926)
Future policy benefits \| Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	153,382	(162,593)	(928,281)	(222,383)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	141,848	(167,330)	(940,465)	(229,926)
Future policy benefits \| Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Future policy benefits \| Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Future policy benefits \| Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Policyholders' account balances
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(123,608)	(7,529)	(133,793)	(1,949)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	(7,943)	(6,057)	(14,698)	(6,960)
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(143,242)	(112,417)	(143,242)	(112,417)
Total gains (losses) (realized/unrealized):
Included in earnings	(11,691)	(98,831)	5,249	(103,508)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(12,621)	(98,831)	5,039	(103,504)
Policyholders' account balances \| Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(11,691)	(98,831)	5,249	(103,508)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(12,621)	(98,831)	5,039	(103,504)
Policyholders' account balances \| Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Policyholders' account balances \| Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Policyholders' account balances \| Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Available-for-sale \| Fixed maturities \| Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	32	(3,163)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	(3,163)
Available-for-sale \| Fixed maturities \| Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Available-for-sale \| Fixed maturities \| Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	1,959	(447)	145	2,353
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	1,959		190
Available-for-sale \| Fixed maturities \| Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	137	8	146
Available-for-sale \| Fixed maturities \| Corporate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	18,274	2,344	1,178	2,882
Purchases	0	0	0	248
Sales	(1)	0	(861)	0
Issuances	0	0	0	0
Settlements	0	(638)	0	(638)
Other	0	0	0	0
Transfers into Level 3	0	639	19,730	639
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	20,232	2,035	20,232	2,035
Total gains (losses) (realized/unrealized):
Included in earnings	1,959	(310)	185	(1,096)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	1,959	0	190	(3,163)
Available-for-sale \| Fixed maturities \| Structured securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	25,324	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	(68)
Other	0	0	0	0
Transfers into Level 3	0	0	0	24,960
Transfers out of Level 3	0	(25,324)	0	(25,324)
Fair Value, end of period	0	0	0	0
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	432
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	$ 0	$ 0	$ 0	$ 0

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

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