Summary of Revenues for Segments and Corporate and Other Activities (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Revenues	$ 2,415	$ 2,371	$ 4,737	$ 4,674
Life Insurance
Segment Reporting Information [Line Items]
Revenues	504	502	984	996
Long-term Care Insurance
Segment Reporting Information [Line Items]
Revenues	872	826	1,728	1,601
Fixed Annuities
Segment Reporting Information [Line Items]
Revenues	257	275	514	527
U.S. Life Insurance
Segment Reporting Information [Line Items]
Revenues	1,633	1,603	3,226	3,124
Canada Mortgage Insurance
Segment Reporting Information [Line Items]
Revenues	180	194	348	386
Australia Mortgage Insurance
Segment Reporting Information [Line Items]
Revenues	134	144	265	287
Other Countries Mortgage Insurance
Segment Reporting Information [Line Items]
Revenues	6	11	15	21
International Mortgage Insurance
Segment Reporting Information [Line Items]
Revenues	320	349	628	694
U.S. Mortgage Insurance
Segment Reporting Information [Line Items]
Revenues	156	151	311	305
International Protection
Segment Reporting Information [Line Items]
Revenues	223	202	430	407
Runoff
Segment Reporting Information [Line Items]
Revenues	89	69	162	112
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	$ (6)	$ (3)	$ (20)	$ 32