Discontinued Operations - Schedule of Assets and Liabilities Reported as Discontinued Operations (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Assets:
Investments, including cash	$ 29
Receivables	23
Property, plant and equipment	974
Other assets	15
Total assets of discontinued operations	1,041
Liabilities:
Short term debt	21
Long term debt	481
Other liabilities	130
Total liabilities of discontinued operations	632
Eliminations [Member]
Assets:
Receivables	(120)
Deferred income taxes	(517)
Total assets of discontinued operations	(637)
HighMount [Member]
Assets:
Investments, including cash	29
Receivables	143
Property, plant and equipment	974
Deferred income taxes	517
Other assets	15
Total assets of discontinued operations	1,678
Liabilities:
Short term debt	21
Long term debt	481
Other liabilities	130
Total liabilities of discontinued operations	$ 632