Condensed Consolidating Financial Information - Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 4,577		$ 3,855	$ 24,032		$ 2,972
Investments	1,371		2,045
Accounts receivable, net	11,719		10,473
Inventories	2,160		2,821
Other current assets	1,341		1,236
Total current assets	21,168		20,430
Long-term investments	28,904		26,929
Reinsurance recoverables	5,274		5,507
Deferred policy acquisition costs	2,795		2,821
Property and equipment	4,448		4,562
Investments in subsidiaries	0		0
Intercompany receivables	0		0
Goodwill	44,462		44,505
Other intangible assets	37,084		39,003
Other assets	2,379		1,630
Separate account assets	8,333		7,839
TOTAL ASSETS	154,847		153,226
Liabilities Abstract
Current insurance and contractholder liabilities	7,180		6,801
Pharmacy and service costs payable	10,857		10,702
Accounts payable	4,502		4,366
Accrued expenses and other liabilities	7,196		7,071
Short-term debt	4,712		2,955
Total current liabilities	34,447		31,895
Non-current insurance and contractholder liabilities	20,090		19,974
Deferred tax liabilities, net	9,284		9,453
Other non-current liabilities	3,919		3,470
Intercompany payables	0		0
Long-term debt	34,041		39,523
Separate account liabilities	8,333		7,839
TOTAL LIABILITIES	110,114		112,154
Redeemable noncontrolling interest	34		37
Total shareholders' equity	44,696		41,028
Other noncontrolling interests	3		7
Total Equity	44,699	$ 43,818	41,035	15,555	$ 14,743	13,711
Total liabilities and equity	154,847		153,226
Consolidation, Eliminations [Member]
Assets
Cash and cash equivalents	0		0	0		0
Investments	0		0
Accounts receivable, net	0		0
Inventories	0		0
Other current assets	0		(210)
Total current assets	0		(210)
Long-term investments	0		0
Reinsurance recoverables	0		0
Deferred policy acquisition costs	0		0
Property and equipment	0		0
Investments in subsidiaries	(183,283)		(173,780)
Intercompany receivables	(41,718)		(39,147)
Goodwill	0		0
Other intangible assets	0		0
Other assets	(207)		(246)
Separate account assets	0		0
TOTAL ASSETS	(225,208)		(213,383)
Liabilities Abstract
Current insurance and contractholder liabilities	0		0
Pharmacy and service costs payable	0		0
Accounts payable	0		0
Accrued expenses and other liabilities	0		(210)
Short-term debt	0		0
Total current liabilities	0		(210)
Non-current insurance and contractholder liabilities	0		0
Deferred tax liabilities, net	(207)		(246)
Other non-current liabilities	0		0
Intercompany payables	(41,718)		(39,147)
Long-term debt	0		0
Separate account liabilities	0		0
TOTAL LIABILITIES	(41,925)		(39,603)
Redeemable noncontrolling interest	0		0
Total shareholders' equity	(183,283)		(173,780)
Other noncontrolling interests	0		0
Total Equity	(183,283)		(173,780)
Total liabilities and equity	(225,208)		(213,383)
Cigna [Member] | Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	0		243	19,889		0
Investments	5		0
Accounts receivable, net	0		0
Inventories	0		0
Other current assets	4		14
Total current assets	9		257
Long-term investments	0		0
Reinsurance recoverables	0		0
Deferred policy acquisition costs	0		0
Property and equipment	0		0
Investments in subsidiaries	72,654		68,969
Intercompany receivables	134		0
Goodwill	0		0
Other intangible assets	0		0
Other assets	27		48
Separate account assets	0		0
TOTAL ASSETS	72,824		69,274
Liabilities Abstract
Current insurance and contractholder liabilities	0		0
Pharmacy and service costs payable	0		0
Accounts payable	26		22
Accrued expenses and other liabilities	316		396
Short-term debt	3,885		0
Total current liabilities	4,227		418
Non-current insurance and contractholder liabilities	0		0
Deferred tax liabilities, net	0		0
Other non-current liabilities	0		0
Intercompany payables	5,766		4,965
Long-term debt	18,135		22,863
Separate account liabilities	0		0
TOTAL LIABILITIES	28,128		28,246
Redeemable noncontrolling interest	0		0
Total shareholders' equity	44,696		41,028
Other noncontrolling interests	0		0
Total Equity	44,696		41,028
Total liabilities and equity	72,824		69,274
Old Cigna [Member] | Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	0		0	0		9
Investments	0		0
Accounts receivable, net	(2)		0
Inventories	0		0
Other current assets	210		59
Total current assets	208		59
Long-term investments	10		10
Reinsurance recoverables	0		0
Deferred policy acquisition costs	0		0
Property and equipment	0		0
Investments in subsidiaries	29,680		27,544
Intercompany receivables	2,950		4,505
Goodwill	0		0
Other intangible assets	0		0
Other assets	221		198
Separate account assets	0		0
TOTAL ASSETS	33,069		32,316
Liabilities Abstract
Current insurance and contractholder liabilities	0		0
Pharmacy and service costs payable	0		0
Accounts payable	0		0
Accrued expenses and other liabilities	410		182
Short-term debt	300		1,500
Total current liabilities	710		1,682
Non-current insurance and contractholder liabilities	0		0
Deferred tax liabilities, net	0		0
Other non-current liabilities	697		685
Intercompany payables	4,512		4,361
Long-term debt	4,816		5,110
Separate account liabilities	0		0
TOTAL LIABILITIES	10,735		11,838
Redeemable noncontrolling interest	0		0
Total shareholders' equity	22,334		20,478
Other noncontrolling interests	0		0
Total Equity	22,334		20,478
Total liabilities and equity	33,069		32,316
Express Scripts Holding Company [Member] | Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	430		633	0		0
Investments	402		0
Accounts receivable, net	0		0
Inventories	0		0
Other current assets	2		0
Total current assets	834		633
Long-term investments	0		0
Reinsurance recoverables	0		0
Deferred policy acquisition costs	0		0
Property and equipment	0		0
Investments in subsidiaries	53,871		52,035
Intercompany receivables	0		0
Goodwill	30,988		31,049
Other intangible assets	8,400		8,400
Other assets	0		0
Separate account assets	0		0
TOTAL ASSETS	94,093		92,117
Liabilities Abstract
Current insurance and contractholder liabilities	0		0
Pharmacy and service costs payable	0		0
Accounts payable	0		0
Accrued expenses and other liabilities	69		129
Short-term debt	0		995
Total current liabilities	69		1,124
Non-current insurance and contractholder liabilities	0		0
Deferred tax liabilities, net	2,001		2,001
Other non-current liabilities	0		0
Intercompany payables	30,754		29,569
Long-term debt	10,949		10,932
Separate account liabilities	0		0
TOTAL LIABILITIES	43,773		43,626
Redeemable noncontrolling interest	0		0
Total shareholders' equity	50,320		48,491
Other noncontrolling interests	0		0
Total Equity	50,320		48,491
Total liabilities and equity	94,093		92,117
Express Scripts Incorporated [Member] | Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	16		43	0		0
Investments	0		0
Accounts receivable, net	2,711		4,206
Inventories	0		0
Other current assets	287		310
Total current assets	3,014		4,559
Long-term investments	0		0
Reinsurance recoverables	0		0
Deferred policy acquisition costs	0		0
Property and equipment	2,298		2,432
Investments in subsidiaries	18,693		17,115
Intercompany receivables	10,171		7,425
Goodwill	0		0
Other intangible assets	17,544		18,962
Other assets	144		68
Separate account assets	0		0
TOTAL ASSETS	51,864		50,561
Liabilities Abstract
Current insurance and contractholder liabilities	0		0
Pharmacy and service costs payable	8,731		8,422
Accounts payable	662		834
Accrued expenses and other liabilities	1,600		1,387
Short-term debt	13		353
Total current liabilities	11,006		10,996
Non-current insurance and contractholder liabilities	0		0
Deferred tax liabilities, net	4,652		5,012
Other non-current liabilities	598		497
Intercompany payables	0		0
Long-term debt	36		24
Separate account liabilities	0		0
TOTAL LIABILITIES	16,292		16,529
Redeemable noncontrolling interest	0		0
Total shareholders' equity	35,572		34,032
Other noncontrolling interests	0		0
Total Equity	35,572		34,032
Total liabilities and equity	51,864		50,561
Medco Health Solutions Incorporated [Member] | Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	0		0	0		0
Investments	0		0
Accounts receivable, net	592		748
Inventories	0		0
Other current assets	24		0
Total current assets	616		748
Long-term investments	0		0
Reinsurance recoverables	0		0
Deferred policy acquisition costs	0		0
Property and equipment	0		0
Investments in subsidiaries	8,385		8,117
Intercompany receivables	2,367		2,335
Goodwill	0		0
Other intangible assets	6,793		7,040
Other assets	86		74
Separate account assets	0		0
TOTAL ASSETS	18,247		18,314
Liabilities Abstract
Current insurance and contractholder liabilities	0		0
Pharmacy and service costs payable	1,355		1,579
Accounts payable	3		4
Accrued expenses and other liabilities	185		189
Short-term debt	503		0
Total current liabilities	2,046		1,772
Non-current insurance and contractholder liabilities	0		0
Deferred tax liabilities, net	1,637		1,685
Other non-current liabilities	246		290
Intercompany payables	0		0
Long-term debt	0		506
Separate account liabilities	0		0
TOTAL LIABILITIES	3,929		4,253
Redeemable noncontrolling interest	0		0
Total shareholders' equity	14,318		14,061
Other noncontrolling interests	0		0
Total Equity	14,318		14,061
Total liabilities and equity	18,247		18,314
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	4,131		2,936	$ 4,143		$ 2,963
Investments	964		2,045
Accounts receivable, net	8,418		5,519
Inventories	2,160		2,821
Other current assets	814		1,063
Total current assets	16,487		14,384
Long-term investments	28,894		26,919
Reinsurance recoverables	5,274		5,507
Deferred policy acquisition costs	2,795		2,821
Property and equipment	2,150		2,130
Investments in subsidiaries	0		0
Intercompany receivables	26,096		24,882
Goodwill	13,474		13,456
Other intangible assets	4,347		4,601
Other assets	2,108		1,488
Separate account assets	8,333		7,839
TOTAL ASSETS	109,958		104,027
Liabilities Abstract
Current insurance and contractholder liabilities	7,180		6,801
Pharmacy and service costs payable	771		701
Accounts payable	3,811		3,506
Accrued expenses and other liabilities	4,616		4,998
Short-term debt	11		107
Total current liabilities	16,389		16,113
Non-current insurance and contractholder liabilities	20,090		19,974
Deferred tax liabilities, net	1,201		1,001
Other non-current liabilities	2,378		1,998
Intercompany payables	686		252
Long-term debt	105		88
Separate account liabilities	8,333		7,839
TOTAL LIABILITIES	49,182		47,265
Redeemable noncontrolling interest	34		37
Total shareholders' equity	60,739		56,718
Other noncontrolling interests	3		7
Total Equity	60,742		56,725
Total liabilities and equity	$ 109,958		$ 104,027