Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net income	$ 2,868	$ 2,555	$ 2,133
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,646	1,326	1,220
Inventory market valuation charge	370	0	0
Pension and other postretirement benefits, net	80	151	(124)
Deferred income taxes	134	(242)	23
Net gain on disposal of assets	7	21	6
Equity method investments, net	25	17	(18)
Changes in the fair value of derivative instruments	4	(3)	(21)
Changes in:
Current receivables	1,292	1,642	(940)
Inventories	80	(786)	(305)
Current accounts payable and accrued liabilities	(2,400)	(1,547)	1,464
All other, net	(31)	18	(21)
Net cash provided by operating activities	4,061	3,110	3,405
Investing activities:
Additions to property, plant and equipment	(1,998)	(1,480)	(1,206)
Acquisitions, net of cash acquired	(1,218)	(2,821)	(1,515)
Disposal of assets	21	27	16
Investments – acquisitions, loans and contributions	(331)	(413)	(151)
Investments—redemptions, repayments and return of capital	4	9	77
All other, net	81	135	23
Net cash used in investing activities	(3,441)	(4,543)	(2,756)
Financing activities:
Long-term debt – borrowings	2,993	3,793	0
Long-term debt – repayments	(2,226)	(548)	(21)
Debt issuance costs	(21)	(22)	(4)
Issuance of common stock	33	26	48
Common stock repurchased	(965)	(2,131)	(2,793)
Dividends paid	(613)	(524)	(484)
Net proceeds from issuance of MPLX LP common units	0	221	0
Distributions to noncontrolling interests	(40)	(27)	(21)
Tax settlement with Marathon Oil Corporation	0	0	39
Contingent consideration payment	(175)	(172)	0
All other, net	27	19	19
Net cash provided by (used in) financing activities	(987)	635	(3,217)
Net decrease in cash and cash equivalents	(367)	(798)	(2,568)
Cash and cash equivalents at beginning of period	1,494	2,292	4,860
Cash and cash equivalents at end of period	$ 1,127	$ 1,494	$ 2,292