Shares and Stockholders' Equity (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Shares and Stockholders' Equity [Abstract]
Deferred compensation plan mark to market adjustment	$ 6	$ (5)

Mark to market adjustments of the entity's stock associated with non-employee directors' deferred compensation plans.

No definition available.

Name:	lnc_DeferredCompensationPlanMarkToMarketAdjustment
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration