Revenues - Customer Concentration, Product Sales (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Major Customer [Line Items]
Product sales									$ 23,362	$ 23,747	$ 22,849
Product [Member]
Revenue, Major Customer [Line Items]
Product sales	$ 5,881	$ 5,463	$ 5,574	$ 5,286	$ 6,001	$ 5,510	$ 5,679	$ 5,343	22,204	22,533	21,795
Product [Member] | AmerisourceBergen Corporation [Member]
Revenue, Major Customer [Line Items]
Product sales									$ 12,301	$ 12,091	$ 10,742
Gross product sales to major customer (as defined) as a percentage of total gross revenues									33.00%	33.00%	31.00%
Product [Member] | McKesson Corporation [Member]
Revenue, Major Customer [Line Items]
Product sales									$ 11,795	$ 11,434	$ 10,625
Gross product sales to major customer (as defined) as a percentage of total gross revenues									31.00%	31.00%	30.00%
Product [Member] | Cardinal Health, Inc. [Member]
Revenue, Major Customer [Line Items]
Product sales									$ 6,538	$ 7,475	$ 7,049
Gross product sales to major customer (as defined) as a percentage of total gross revenues									17.00%	20.00%	20.00%