Financial Instruments - Other Noncurrent Liabilities (Detail) - USD ($) $ in Millions		1 Months Ended				3 Months Ended		9 Months Ended
		Apr. 30, 2018	Dec. 31, 2017	Aug. 31, 2017	Jun. 30, 2017	Sep. 30, 2018	Jul. 01, 2018	Sep. 30, 2018	Aug. 31, 2018	Jun. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net			$ 36,562			$ 36,012		$ 36,012
Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	[1]		$ 34,765			34,337		34,337
EU [Member] | Mylotarg [Member]
Finite-Lived Intangible Assets [Line Items]
Term over which fixed annual payments are to be made		10 years
Aggregate amount of guaranteed fixed annual payments to be made in connection with research and development arrangement		$ 301
EU [Member] | Mylotarg [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net		$ 240
Lump sum payment for liability buyout										$ 224
Non-cash gain from buyout transaction							$ 17	17
EU [Member] | Besponsa [Member]
Finite-Lived Intangible Assets [Line Items]
Term over which fixed annual payments are to be made					9 years
Aggregate amount of guaranteed fixed annual payments to be made in connection with research and development arrangement					$ 148
EU [Member] | Besponsa [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net					$ 123	121		121
EU [Member] | Besponsa [Member] | Developed Technology Rights [Member] | Other Current Liabilities [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net						3		3
EU [Member] | Besponsa [Member] | Developed Technology Rights [Member] | Other Noncurrent Liabilities [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net						118		118
U.S. [Member] | Bosulif [Member]
Finite-Lived Intangible Assets [Line Items]
Term over which fixed annual payments are to be made			10 years
Aggregate amount of guaranteed fixed annual payments to be made in connection with research and development arrangement			$ 416
U.S. [Member] | Bosulif [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net			$ 364			208		208
Lump sum payment for liability buyout									$ 71
Non-cash gain from buyout transaction						9
U.S. [Member] | Bosulif [Member] | Developed Technology Rights [Member] | Other Current Liabilities [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net						23		23
U.S. [Member] | Bosulif [Member] | Developed Technology Rights [Member] | Other Noncurrent Liabilities [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net						185		185
U.S. [Member] | Besponsa [Member]
Finite-Lived Intangible Assets [Line Items]
Term over which fixed annual payments are to be made				9 years
Aggregate amount of guaranteed fixed annual payments to be made in connection with research and development arrangement				$ 296
U.S. [Member] | Besponsa [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net				$ 248		240		240
U.S. [Member] | Besponsa [Member] | Developed Technology Rights [Member] | Other Current Liabilities [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net						7		7
U.S. [Member] | Besponsa [Member] | Developed Technology Rights [Member] | Other Noncurrent Liabilities [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net						$ 233		$ 233

[1] The changes in the gross carrying amount of Developed technology rights and IPR&D primarily reflect (i) the transfer of $2.7 billion from IPR&D to Developed technology rights to reflect the approval of Xtandi in the U.S. for the treatment of men with non-metastatic castration-resistant prostate cancer, which is being developed through a collaboration with Astellas, and (ii) $240 million of Developed technology rights recorded in connection with the EU approval of Mylotarg (see Note 7E).