Schedule I - Condensed Financial Information, Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Net investment (income)									$ (1,480)	$ (1,226)	$ (1,147)
Total revenues	$ 14,300	$ 11,457	$ 11,480	$ 11,413	$ 10,632	$ 10,372	$ 10,374	$ 10,428	48,650	41,806	39,838
Operating expenses:
Selling, Genernal and Administrative Expense									11,934	10,030	9,790
Total operating expenses									44,490	37,864	36,750
Income from operations									4,160	3,942	3,088
Interest expense and other									(498)	(252)	(278)
Debt extinguishment costs						(321)			0	(321)	0
Realized investment (gains) losses									81	(237)	(169)
Income (loss) before income taxes	228	1,033	1,102	1,218	758	824	1,134	890	3,581	3,606	2,979
Income tax expense (benefit)									935	1,374	1,136
Shareholders' net income	$ 144	$ 772	$ 806	$ 915	$ 266	$ 560	$ 813	$ 598	2,637	2,237	1,867
Shareholders' other comprehensive income (loss), net of tax:
Net unrealized appreciation (depreciation) on securities and derivatives									(365)	(37)	(60)
Net translation (losses) gains on foreign currencies									(152)	304	(95)
Postretirement benefits liability adjustment									127	33	23
Shareholders' other comprehensive income (loss)									(390)	300	(132)
Shareholders' comprehensive income (loss)									2,247	2,537	1,735
Cigna [Member]
Revenues
Net investment (income)									123
Total revenues									123
Operating expenses:
Selling, Genernal and Administrative Expense									200
Total operating expenses									200
Income from operations									(77)
Interest expense and other									(244)
Intercompany interest income (expense)									(5)
Debt extinguishment costs									0
Realized investment (gains) losses									(1)
Income (loss) before income taxes									(327)
Income tax expense (benefit)									(74)
(Loss) of parent company									(253)
Equity in income from subsidiaries									2,890
Shareholders' net income									2,637
Shareholders' other comprehensive income (loss), net of tax:
Net unrealized appreciation (depreciation) on securities and derivatives									(365)
Net translation (losses) gains on foreign currencies									(152)
Postretirement benefits liability adjustment									127
Shareholders' other comprehensive income (loss)									(390)
Shareholders' comprehensive income (loss)									$ 2,247
Old Cigna [Member]
Revenues
Net investment (income)										0	0
Total revenues										0	0
Operating expenses:
Selling, Genernal and Administrative Expense										195	281
Total operating expenses										195	281
Income from operations										(195)	(281)
Interest expense and other										(246)	(244)
Intercompany interest income (expense)										(18)	(3)
Debt extinguishment costs										(321)	0
Realized investment (gains) losses										0	0
Income (loss) before income taxes										(780)	(528)
Income tax expense (benefit)										(194)	(146)
(Loss) of parent company										(586)	(382)
Equity in income from subsidiaries										2,823	2,249
Shareholders' net income										2,237	1,867
Shareholders' other comprehensive income (loss), net of tax:
Net unrealized appreciation (depreciation) on securities and derivatives										(37)	(60)
Net translation (losses) gains on foreign currencies										304	(95)
Postretirement benefits liability adjustment										33	23
Shareholders' other comprehensive income (loss)										300	(132)
Shareholders' comprehensive income (loss)										$ 2,537	$ 1,735