Schedule I Condensed Statements of Operations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating costs and expenses:
Depreciation and amortization	$ 1,455	$ 1,341	$ 1,276
Total operating costs and expenses	8,981	8,489	8,625
Operating income (loss)	2,567	2,684	2,502
Other income (expense):
Interest expense	(1,176)	(1,196)	(1,225)
Other, net	56	(7)	45
Total other income (expense)	(992)	(1,091)	(1,037)
Income (loss) before income tax expense (benefit) and equity income	1,575	1,593	1,465
Income tax benefit	148	294	198
Equity income	68	53	43
Net income	1,495	1,352	1,310
Net income attributable to noncontrolling interests	23	21	72
Net income attributable to MEHC shareholders	1,472	1,331	1,238
Parent [Member]
Operating costs and expenses:
General and administration	31	35	42
Depreciation and amortization	1	0	0
Total operating costs and expenses	32	35	42
Operating income (loss)	(32)	(35)	(42)
Other income (expense):
Interest expense	(362)	(396)	(425)
Other, net	10	(38)	23
Total other income (expense)	(352)	(434)	(402)
Income (loss) before income tax expense (benefit) and equity income	(384)	(469)	(444)
Income tax benefit	(201)	(194)	(220)
Equity income	1,656	1,607	1,462
Net income	1,473	1,332	1,238
Net income attributable to noncontrolling interests	1	1	0
Net income attributable to MEHC shareholders	$ 1,472	$ 1,331	$ 1,238