Shares and Stockholders' Equity - Reconciliation of the Denominator Calculations of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Stockholders' Equity Note [Abstract]
Net income (loss) available to common stockholders – basic	$ (206)	$ (756)
Deferred units of LNC stock in our deferred compensation plans	(5)	0
Net income (loss) available to common stockholders	$ (211)	$ (756)
Weighted-average shares, as used in basic calculation (in shares)	191,891,461	171,321,440
Incremental common shares from assumed exercise or issuance of stock-based incentive compensation awards (in shares)	3,879,235	2,765,580
Average deferred compensation shares (in shares)	725,848	0
Weighted-average shares, as used in diluted calculation (in shares)	196,496,544	174,087,020
Net income (loss) per share:
Basic (in dollars per share)	$ (1.08)	$ (4.41)
Diluted (in dollars per share)	$ (1.10)	$ (4.41)