Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Supplemental Cash Flow Information [Abstract]
Income Taxes Paid Net, Discontinued Operations	$ 1,312		$ 2,270		$ 2,336
Operating activities:
Interest paid (net of amounts capitalized)	289		307		225
Income taxes paid to taxing authorities	1,679	[1]	3,904	[1]	4,974	[1]
Commercial paper:
Issuances	2,345		10,870		13,880
Repayments	(2,480)		(10,935)		(13,680)
Net commercial paper	(135)		(65)		200
Noncash investing and financing activities:
Asset retirement costs capitalized, excluding acquisitions	151		290		199
Change in capital expenditure accrual	335		6		165
Liabilities Assumed	0		0		109
Asset Retirement Obligation, Liabilities Transferred	359		92		8
Debt payments made by United States Steel	$ 0		$ 0		$ 20

[1] Income taxes paid to taxing authorities includes $1,312 million, $2,270 million and $2,336 million in 2014, 2013, and 2012