Fair Values of Financial Instruments (Carrying Amounts and Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Fixed maturity securities, available for sale, fair value	$ 47,538,893	$ 51,580,490
Derivative instruments	1,310,954	1,355,989
Other investments	590,078	492,301
Coinsurance deposits (net of allowance for credit losses of $1,888 as of 2020 and $0 as of 2019)	4,844,927	5,115,013
Liabilities
Policy benefit reserves	61,768,246	61,893,945
Carrying Amount
Assets
Fixed maturity securities, available for sale, fair value	47,538,893	51,580,490
Mortgage loans on real estate	4,165,489	3,448,793
Derivative instruments	1,310,954	1,355,989
Other investments	590,078	492,301
Cash and cash equivalents	9,095,522	2,293,392
Coinsurance deposits (net of allowance for credit losses of $1,888 as of 2020 and $0 as of 2019)	4,844,927	5,115,013
Liabilities
Policy benefit reserves	61,406,599	61,540,992
Single premium immediate annuity (SPIA) benefit reserves	240,226	255,698
Notes payable	495,668	495,116
Subordinated debentures	78,112	157,265
Carrying Amount \| Interest Rate Caps
Assets
Interest rate derivative assets	0	6
Fair Value
Assets
Fixed maturity securities, available for sale, fair value	47,538,893	51,580,490
Mortgage loans on real estate	4,327,885	3,536,446
Derivative instruments	1,310,954	1,355,989
Other investments	590,078	492,301
Cash and cash equivalents	9,095,522	2,293,392
Coinsurance deposits (net of allowance for credit losses of $1,888 as of 2020 and $0 as of 2019)	4,411,051	4,635,926
Liabilities
Policy benefit reserves	52,928,174	51,800,247
Single premium immediate annuity (SPIA) benefit reserves	247,679	263,773
Notes payable	567,345	541,520
Subordinated debentures	87,951	168,357
Fair Value \| Interest Rate Caps
Assets
Interest rate derivative assets	$ 0	$ 6

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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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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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