Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Compensation and employee benefits	$ 810	$ 529
Accruals and reserves	371	371
Chargebacks and rebates	477	417
Advance payments	615	867
Net operating losses and other credit carryforwards	838	228
Other	406	353
Total deferred tax assets	3,517	2,765
Valuation allowances	(731)	(103)
Total net deferred tax assets	2,786	2,662
Deferred tax liabilities
Excess of book basis over tax basis of intangible assets	(2,712)	(2,940)
Excess of book basis over tax basis in investments	(249)	(211)
Other	(440)	(250)
Total deferred tax liabilities	(3,401)	(3,401)
Net deferred tax liabilities	(615)	$ (739)
State And Local Jurisdiction
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	1,000
Tax credit carryforwards	188
Foreign Country
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	2,900
Operating loss carryforwards with expiration between 2018 and 2023	$ 2,800