Discontinued Operations - Schedule of Discontinued Operations Reflected in Consolidated Condensed Statements of Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Expenses:
Income (loss) from discontinued operations	$ 29		$ (36)	$ (364)	$ (108)
HighMount [Member]
Revenues:
Other revenue, primarily operating	49		61	150	195
Total	49		61	150	195
Expenses:
Impairment of natural gas and oil properties			65	29	210
Operating	54		52	165	162
Interest	3		4	8	13
Total	57		121	202	385
Income (loss) before income tax	(8)		(60)	(52)	(190)
Income tax (expense) benefit	3		22	2	69
Results of discontinued operations, net of income tax	(5)		(38)	(50)	(121)
Impairment loss/loss on sale, net of tax (expense) benefit	30	(167)		(137)
Income (loss) from discontinued operations	25		(38)	(187)	(121)
CAC [Member]
Revenues:
Net investment income	14		42	94	128
Investment gains	1		3	3	8
Other			1		1
Total	15		46	97	137
Expenses:
Insurance claims and policyholders' benefits	12		36	75	105
Other operating expenses			6	2	8
Total	12		42	77	113
Income (loss) before income tax	3		4	20	24
Income tax (expense) benefit	(2)		(3)	(6)	(10)
Results of discontinued operations, net of income tax	1		1	14	14
Impairment loss/loss on sale, net of tax (expense) benefit	3			(211)
Amounts attributable to noncontrolling interests			1	20	(1)
Income (loss) from discontinued operations	$ 4		$ 2	$ (177)	$ 13