Shares and Stockholders' Equity - Reconciliation of the Denominator Calculations of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Stockholders' Equity Note [Abstract]
Net income (loss) available to common stockholders – basic	$ 411	$ (562)	$ 343	$ 1,508
Deferred units of LNC stock in our deferred compensation plans	0	0	0	3
Net income (loss) available to common stockholders	$ 411	$ (562)	$ 343	$ 1,511
Weighted-average shares, as used in basic calculation (in shares)	190,826,396	170,773,438	179,845,834	170,482,264
Incremental common shares from assumed exercise or issuance of stock-based incentive compensation awards (in shares)	3,477,709	2,075,432	3,005,449	1,575,034
Average deferred compensation shares (in shares)	0	0	0	710,256
Weighted-average shares, as used in diluted calculation (in shares)	194,304,105	172,848,870	182,851,283	172,767,554
Net income (loss) per share:
Basic (in dollars per share)	$ 2.15	$ (3.29)	$ 1.90	$ 8.85
Diluted (in dollars per share)	$ 2.12	$ (3.29)	$ 1.87	$ 8.75