Schedule I - Parent Company Financial Information (Condensed Statements of Income) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues:
Total revenues	$ 10,187	[1]	$ 10,319	$ 10,321	$ 10,486	$ 9,557	$ 9,651	$ 9,699	$ 10,219	$ 41,313	$ 39,126	$ 36,832
Expenses:
Operating costs										6,355	5,830	5,395
Depreciation										309	263	249
Interest										140	105	109
Benefit for income taxes										690	689	816
Net income	(30)	[1]	368	420	473	192	426	356	248	1,231	1,222	1,419
Parent Company
Revenues:
Management fees charged to operating subsidiaries										1,370	1,220	1,272
Investment and other income, net										3	5	8
Total revenues										1,373	1,225	1,280
Expenses:
Operating costs										1,366	1,229	1,270
Depreciation										193	172	164
Interest										141	106	107
Total operating expense										1,700	1,507	1,541
Loss before income taxes and equity in net earnings of subsidiaries										(327)	(282)	(261)
Benefit for income taxes										(107)	(102)	(81)
Loss before equity in net earnings of subsidiaries										(220)	(180)	(180)
Equity in net earnings of subsidiaries										1,451	1,402	1,599
Net income										$ 1,231	$ 1,222	$ 1,419

[1] The sum of quarterly amounts does not equal full year results due to the anti-dilutive impact of a loss in the fourth quarter. The fourth quarter includes an expense of $243 million ($154 million after tax, or $0.99 per diluted common share) for reserve strengthening associated with our closed block of long-term care insurance policies.