Derivative Instruments (Gains (Losses) On Derivative Instruments Designated As Cash Flow Hedges) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income	$ 1,232	$ 1,262	$ 2,465	$ 2,499
Offset to realized gain (loss)	(7)	(10)	5	(49)
Offset to interest and debt expense	(68)	(63)	(159)	(127)
Designated as Hedging Instrument [Member] \| Cash Flow Hedges [Member] \| Other Comprehensive Income (Loss) [Member]
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income	6	5	13	11
Offset to realized gain (loss)				5
Offset to interest and debt expense	$ 2	$ (5)	$ (2)	$ (9)

This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting, losses recognized for other than temporary impairments (OTTI) of the subject investments, derivatives and embedded derivatives gains and losses and gains and losses from reinsurance embedded derivatives.

No definition available.

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