Discontinued Operations - Schedule of Discontinued Operations Reflected in Consolidated Condensed Statements of Income (Detail) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Expenses:
Loss on sale, net of tax benefit					$ 3
Income (loss) from discontinued operations	$ (7)	$ 29	$ (187)	$ (206)	(371)	$ (554)
HighMount [Member]
Revenues:
Other revenue, primarily operating					150	259
Total					150	259
Expenses:
Impairment of goodwill						584
Impairment of natural gas and oil properties					29	291
Operating					173	252
Interest					8	17
Total					210	1,144
Income (loss) before income tax					(60)	(885)
Income tax (expense) benefit					4	311
Results of discontinued operations, net of income tax					(56)	(574)
Impairment loss, net of tax benefit					(138)
Income (loss) from discontinued operations					(194)	(574)
CAC [Member]
Revenues:
Net investment income					94	168
Investment gains					3	11
Other revenues						2
Total					97	181
Expenses:
Insurance claims and policyholders' benefits					75	141
Other operating expenses					2	3
Operating					77	144
Income (loss) before income tax					20	37
Income tax (expense) benefit					(6)	(15)
Results of discontinued operations, net of income tax					14	22
Loss on sale, net of tax benefit					(211)
Amounts attributable to noncontrolling interests					20	(2)
Income (loss) from discontinued operations					$ (177)	$ 20