Discontinued Operations - Schedule of Discontinued Operations Reflected in Consolidated Condensed Statements of Income (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2014 USD ($)
Expenses:
Loss from discontinued operations	$ (371)
HighMount [Member]
Revenues:
Other revenue, primarily operating	150
Total	150
Expenses:
Impairment of natural gas and oil properties	29
Operating	173
Interest	8
Total	210
Income (loss) before income tax	(60)
Income tax (expense) benefit	4
Results of discontinued operations, net of income tax	(56)
Impairment loss, net of tax benefit	(138)
Loss from discontinued operations	(194)
CAC [Member]
Revenues:
Net investment income	94
Investment gains	3
Total	97
Expenses:
Insurance claims and policyholders' benefits	75
Other operating expenses	2
Operating	77
Income (loss) before income tax	20
Income tax (expense) benefit	(6)
Results of discontinued operations, net of income tax	14
Loss on sale, net of tax benefit	(211)
Amounts attributable to noncontrolling interests	20
Loss from discontinued operations	$ (177)