Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities:
Net income	$ 2,675	$ 5,457
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	186	169
Amortization expense	868	902
Stock-based compensation expense	479	670
Deferred income taxes	(796)	10
Net unrealized gains from equity securities	(312)	(149)
Up-front and milestone expense related to collaborative and other arrangements	4,291	0
Other	159	163
Changes in operating assets and liabilities:
Accounts receivable, net	33	367
Inventories	(35)	(191)
Prepaid expenses and other	(225)	749
Accounts payable	(142)	(217)
Income taxes payable	107	(1,551)
Accrued liabilities and other	(724)	(324)
Net cash provided by operating activities	6,564	6,055
Investing Activities:
Purchases of marketable debt securities	(24,057)	(5,786)
Proceeds from sales of marketable debt securities	4,522	1,201
Proceeds from maturities of marketable debt securities	17,639	17,021
Up-front and milestone payments related to collaborative and other arrangements	(4,281)	0
Purchases of equity securities	1,251	132
Capital expenditures	(622)	(676)
Other	198	8
Net cash provided by (used in) investing activities	(8,248)	11,620
Financing Activities:
Proceeds from issuances of common stock	182	239
Repurchases of common stock	(1,644)	(1,938)
Repayments of debt and other obligations	(2,750)	(6,250)
Payments of dividends	(2,421)	(2,235)
Other	(105)	(464)
Net cash used in financing activities	(6,738)	(10,648)
Effect of exchange rate changes on cash and cash equivalents	(44)	(46)
Net change in cash and cash equivalents	(8,466)	6,981
Cash and cash equivalents at beginning of period	17,940	7,588
Cash and cash equivalents at end of period	$ 9,474	$ 14,569