Fair Values of Financial Instruments (Fair Values and Carrying Amounts of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets
Fixed maturity securities, available for sale, fair value	$ 50,738,792	$ 51,580,490
Derivative instruments	672,958	1,355,989
Other investments	479,099	492,301
Coinsurance deposits (net of allowance for credit losses of $3,948 as of 2020 and $0 as of 2019)	4,962,859	5,115,013
Liabilities
Policy benefit reserves	61,669,232	61,893,945
Carrying Amount
Assets
Fixed maturity securities, available for sale, fair value	50,738,792	51,580,490
Mortgage loans on real estate	3,958,233	3,448,793
Derivative instruments	672,958	1,355,989
Other investments	479,099	492,301
Cash and cash equivalents	2,408,635	2,293,392
Coinsurance deposits (net of allowance for credit losses of $3,948 as of 2020 and $0 as of 2019)	4,962,859	5,115,013
Liabilities
Policy benefit reserves	61,312,957	61,540,992
Single premium immediate annuity (SPIA) benefit reserves	243,910	255,698
Notes payable	495,388	495,116
Subordinated debentures	77,964	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	50,738,792	51,580,490
Mortgage loans on real estate	4,044,873	3,536,446
Derivative instruments	672,958	1,355,989
Other investments	479,099	492,301
Cash and cash equivalents	2,408,635	2,293,392
Coinsurance deposits (net of allowance for credit losses of $3,948 as of 2020 and $0 as of 2019)	4,527,374	4,635,926
Liabilities
Policy benefit reserves	51,865,732	51,800,247
Single premium immediate annuity (SPIA) benefit reserves	251,599	263,773
Notes payable	543,520	541,520
Subordinated debentures	74,084	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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Amount, before effect of reinsurance, of present value of future benefit to be paid to or on behalf of policyholder and related expense less present value of future net premium receivable under insurance contract.

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