Future policy benefits (Rollforward) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021		Jul. 01, 2023	Jul. 01, 2022	Jan. 01, 2021	Dec. 31, 2020
Liability for Future Policy Benefit, Activity [Line Items]
Net liability for future policy benefits, per consolidated balance sheet		$ 13,888		$ 10,476		$ 7,837				$ 7,652
Weighted-average duration (years)		19 years 4 months 24 days		17 years 6 months		17 years 1 month 6 days
Cigna's Life Insurance Business in Asian Markets
Liability for Future Policy Benefit, Activity [Line Items]
Net liability for future policy benefits, per consolidated balance sheet									$ 3,856
Huatai Group [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Net liability for future policy benefits, per consolidated balance sheet								$ 2,287
Life Insurance [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		$ 14,867		$ 4,315		$ 4,583
Beginning balance at original discount rate		16,693		15,529		3,993					$ 3,953
Effect of changes in cash flow assumptions				(756)		13					(33)
Effect of actual variances from expected experience				(5)		(95)					(169)
Adjusted beginning of period balance		14,768		3,911		3,751
Acquisition		1,850		11,571
Issuances		2,170		1,044		553
Interest accrual		691		436		312
Net premiums collected (1)		(2,320)	[1]	(1,332)	[2]	(543)	[3]
Other (including foreign exchange)		466		(101)		(80)
Ending balance at original discount rate				14,768		3,911
Effect of changes in discount rate assumptions		(657)		(662)		322
Balance – end of period		16,036		14,867		4,315
Balance – beginning of period		23,324		10,387		11,100
Beginning balance at original discount rate		28,303		24,456		9,019					8,905
Effect of changes in cash flow assumptions				(795)		17					(36)
Effect of actual variances from expected experience				15		(102)					(166)
Adjusted beginning of period balance		23,676		8,934		8,703
Acquisition		4,072		15,447
Issuances		2,170		1,044		553
Interest accrual		1,023		664		480
Benefits payments		(2,135)		(1,285)		(613)
Other (including foreign exchange)		(503)		348		104
Ending balance at original discount rate				23,676		8,934
Effect of changes in discount rate assumptions		(841)		(1,132)		1,368
Balance – end of period		27,462		23,324		10,387
Net liability for future policy benefits		11,426		8,457		6,072
Deferred profit liability		1,253		869		613
Net liability for future policy benefits, per consolidated balance sheet		12,679		9,326		6,685
Less: Reinsurance recoverable on future policy benefits		233		251		210
Net liability for future policy benefits, after reinsurance recoverable		12,446		9,075		6,475
Other Segments [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Net liability for future policy benefits, per consolidated balance sheet	[4]	1,209		1,150		1,152
Term Life Insurance | Life Insurance [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		1,806		422		371
Beginning balance at original discount rate		1,992		1,867		397					322
Effect of changes in cash flow assumptions				22		35					(4)
Effect of actual variances from expected experience				(9)		(35)					(82)
Adjusted beginning of period balance		1,880		397		236
Issuances		190		169		183
Interest accrual		71		71		97
Net premiums collected (1)		(255)	[1]	(185)	[2]	(107)	[3]
Other (including foreign exchange)		(103)		54		(12)
Ending balance at original discount rate				1,880		397
Effect of changes in discount rate assumptions		(402)		(61)		25
Balance – end of period		1,590		1,806		422
Balance – beginning of period		2,321		832		739
Beginning balance at original discount rate		2,749		2,447		775					630
Effect of changes in cash flow assumptions				15		34					(7)
Effect of actual variances from expected experience				(4)		(36)					(73)
Adjusted beginning of period balance		2,458		773		550
Issuances		190		169		183
Interest accrual		90		83		105
Benefits payments		(238)		(176)		(102)
Other (including foreign exchange)		232		(5)		(39)
Ending balance at original discount rate				2,458		773
Effect of changes in discount rate assumptions		(495)		(126)		57
Balance – end of period		2,254		2,321		832
Net liability for future policy benefits		664		515		410
Deferred profit liability		267		201		128
Net liability for future policy benefits, per consolidated balance sheet		931		716		538				454
Less: Reinsurance recoverable on future policy benefits		82		93		119
Net liability for future policy benefits, after reinsurance recoverable		$ 849		$ 623		$ 419
Weighted-average duration (years)		10 years 6 months		9 years 2 months 12 days		10 years 7 months 6 days
Term Life Insurance | Life Insurance [Member] | Cigna's Life Insurance Business in Asian Markets
Liability for Future Policy Benefit, Activity [Line Items]
Acquisition				$ 1,361
Acquisition				1,593
Term Life Insurance | Life Insurance [Member] | Huatai Group [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Acquisition		$ 3
Acquisition		17
Whole Life Insurance | Life Insurance [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		2,308		1,343		$ 1,395
Beginning balance at original discount rate		3,945		2,361		1,245					1,201
Effect of changes in cash flow assumptions				40		3					(24)
Effect of actual variances from expected experience				88		69					2
Adjusted beginning of period balance		2,489		1,317		1,179
Issuances		318		230		229
Interest accrual		87		55		51
Net premiums collected (1)		(585)	[1]	(273)	[2]	(161)	[3]
Other (including foreign exchange)		54		(50)		(53)
Ending balance at original discount rate				2,489		1,317
Effect of changes in discount rate assumptions		5		(53)		98
Balance – end of period		3,950		2,308		1,343
Balance – beginning of period		5,696		4,493		4,886
Beginning balance at original discount rate		9,991		5,874		3,540					3,503
Effect of changes in cash flow assumptions				44		5					(24)
Effect of actual variances from expected experience				98		72					(2)
Adjusted beginning of period balance		6,016		3,617		3,477
Issuances		318		230		229
Interest accrual		252		176		152
Benefits payments		(333)		(248)		(174)
Other (including foreign exchange)		79		179		144
Ending balance at original discount rate				6,016		3,617
Effect of changes in discount rate assumptions		72		(178)		953
Balance – end of period		10,063		5,696		4,493
Net liability for future policy benefits		6,113		3,388		3,150
Deferred profit liability		804		531		387
Net liability for future policy benefits, per consolidated balance sheet		6,917		3,919		3,537				3,767
Less: Reinsurance recoverable on future policy benefits		45		49		51
Net liability for future policy benefits, after reinsurance recoverable		$ 6,872		$ 3,870		$ 3,486
Weighted-average duration (years)		25 years 9 months 18 days		25 years 1 month 6 days		21 years 6 months
Whole Life Insurance | Life Insurance [Member] | Cigna's Life Insurance Business in Asian Markets
Liability for Future Policy Benefit, Activity [Line Items]
Acquisition				$ 1,082
Acquisition				2,278
Whole Life Insurance | Life Insurance [Member] | Huatai Group [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Acquisition		$ 1,690
Acquisition		3,659
Accident and Health [Member] | Life Insurance [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		10,711		2,520		$ 2,782
Beginning balance at original discount rate		10,692		11,258		2,323					2,398
Effect of changes in cash flow assumptions				(820)		(25)					(4)
Effect of actual variances from expected experience				(84)		(129)					(89)
Adjusted beginning of period balance		10,354		2,169		2,305
Issuances		1,653		639		135
Interest accrual		531		309		164
Net premiums collected (1)		(1,457)	[1]	(859)	[2]	(270)	[3]
Other (including foreign exchange)		534		(105)		(11)
Ending balance at original discount rate				10,354		2,169
Effect of changes in discount rate assumptions		(260)		(547)		197
Balance – end of period		10,432		10,711		2,520
Balance – beginning of period		15,038		4,935		5,351
Beginning balance at original discount rate		15,071		15,855		4,585					4,668
Effect of changes in cash flow assumptions				(858)		(37)					(4)
Effect of actual variances from expected experience				(78)		(138)					(90)
Adjusted beginning of period balance		14,919		4,410		4,574
Issuances		1,653		639		135
Interest accrual		672		401		221
Benefits payments		(1,551)		(855)		(337)
Other (including foreign exchange)		(785)		181		8
Ending balance at original discount rate				14,919		4,410
Effect of changes in discount rate assumptions		(421)		(817)		350
Balance – end of period		14,650		15,038		4,935
Net liability for future policy benefits		4,218		4,327		2,415
Deferred profit liability		165		126		94
Net liability for future policy benefits, per consolidated balance sheet		4,383		4,453		2,509				2,569
Less: Reinsurance recoverable on future policy benefits		106		109		40
Net liability for future policy benefits, after reinsurance recoverable		$ 4,277		$ 4,344		$ 2,469
Weighted-average duration (years)		10 years 4 months 24 days		10 years 8 months 12 days		10 years 6 months
Accident and Health [Member] | Life Insurance [Member] | Cigna's Life Insurance Business in Asian Markets
Liability for Future Policy Benefit, Activity [Line Items]
Acquisition				$ 9,105
Acquisition				11,441
Accident and Health [Member] | Life Insurance [Member] | Huatai Group [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Acquisition		$ 145
Acquisition		163
Accident and Health [Member] | Overseas General Insurance [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Net liability for future policy benefits, per consolidated balance sheet										773
Insurance, Other [Member] | Life Insurance [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Balance – beginning of period		42		30		$ 35
Beginning balance at original discount rate		64		43		28					32
Effect of changes in cash flow assumptions				2		0					(1)
Effect of actual variances from expected experience				0		0					0
Adjusted beginning of period balance		45		28		31
Issuances		9		6		6
Interest accrual		2		1		0
Net premiums collected (1)		(23)	[1]	(15)	[2]	(5)	[3]
Other (including foreign exchange)		(19)		0		(4)
Ending balance at original discount rate				45		28
Effect of changes in discount rate assumptions		0		(1)		2
Balance – end of period		64		42		30
Balance – beginning of period		269		127		124
Beginning balance at original discount rate		492		280		119					104
Effect of changes in cash flow assumptions				4		15					(1)
Effect of actual variances from expected experience				(1)		0					$ (1)
Adjusted beginning of period balance		283		134		102
Issuances		9		6		6
Interest accrual		9		4		2
Benefits payments		(13)		(6)		0
Other (including foreign exchange)		(29)		(7)		(9)
Ending balance at original discount rate				283		134
Effect of changes in discount rate assumptions		3		(11)		8
Balance – end of period		495		269		127
Net liability for future policy benefits		431		227		97
Deferred profit liability		17		11		4
Net liability for future policy benefits, per consolidated balance sheet		448		238		101				$ 89
Less: Reinsurance recoverable on future policy benefits		0		0		0
Net liability for future policy benefits, after reinsurance recoverable		$ 448		$ 238		$ 101
Weighted-average duration (years)		15 years		14 years		26 years 3 months 18 days
Insurance, Other [Member] | Life Insurance [Member] | Cigna's Life Insurance Business in Asian Markets
Liability for Future Policy Benefit, Activity [Line Items]
Acquisition				$ 23
Acquisition				$ 135
Insurance, Other [Member] | Life Insurance [Member] | Huatai Group [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Acquisition		$ 12
Acquisition		$ 233

[1] Net premiums collected represent the portion of gross premiums collected from policyholders that is used to fund expected benefit.

[2] Net premiums collected represent the portion of gross premiums collected from policyholders that is used to fund expected benefit

[3] Net premiums collected represent the portion of gross premiums collected from policyholders that is used to fund expected benefit.

[4] Other business principally comprises certain Overseas General Insurance accident and health (A&H) policies and certain Chubb Life Re business.