Investments - Schedule of Increase (Decrease) in Payables for Collateral on Investments (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Investments [Abstract]
Collateral payable for derivative investments	$ 1,917	$ (2,355)	$ 2,595
Securities pledged under securities lending agreements	(93)	57	126
Investments pledged for FHLBI	(480)	0	0
Total increase (decrease) in payables for collateral on investments	$ 1,344	$ (2,298)	$ 2,721

The net change during the reporting period in the amount of cash that is received related to securities pledged for Federal Home Loan Bank of Indianapolis.

No definition available.

Name:	cik0000726865_IncreaseDecreaseInCashCollateralForSecuritiesPledgedForFHLBI
Namespace Prefix:	cik0000726865_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration