Fair Values of Financial Instruments (Fair Values and Carrying Amounts of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets
Fixed maturity securities, available for sale, fair value	$ 47,704,867	$ 51,580,490
Derivative instruments	207,265	1,355,989
Other investments	497,598	492,301
Coinsurance deposits (net of allowance for credit losses of $4,559 as of 2020 and $0 as of 2019)	4,933,992	5,115,013
Liabilities
Policy benefit reserves	60,619,047	61,893,945
Carrying Amount
Assets
Fixed maturity securities, available for sale, fair value	47,704,867	51,580,490
Mortgage loans on real estate	3,668,625	3,448,793
Derivative instruments	207,265	1,355,989
Other investments	497,598	492,301
Cash and cash equivalents	1,833,099	2,293,392
Coinsurance deposits (net of allowance for credit losses of $4,559 as of 2020 and $0 as of 2019)	4,933,992	5,115,013
Liabilities
Policy benefit reserves	60,266,132	61,540,992
Single premium immediate annuity (SPIA) benefit reserves	247,886	255,698
Notes payable	495,251	495,116
Subordinated debentures	77,893	157,265
Amounts due under repurchase agreements	186,105	0
Carrying Amount \| Interest Rate Caps
Assets
Interest rate derivative assets	0	6
Fair Value
Assets
Fixed maturity securities, available for sale, fair value	47,704,867	51,580,490
Mortgage loans on real estate	3,727,294	3,536,446
Derivative instruments	207,265	1,355,989
Other investments	497,598	492,301
Cash and cash equivalents	1,833,099	2,293,392
Coinsurance deposits (net of allowance for credit losses of $4,559 as of 2020 and $0 as of 2019)	4,577,710	4,635,926
Liabilities
Policy benefit reserves	51,934,397	51,800,247
Single premium immediate annuity (SPIA) benefit reserves	255,848	263,773
Notes payable	483,405	541,520
Subordinated debentures	70,602	168,357
Amounts due under repurchase agreements	186,105	0
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 currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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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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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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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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