Goodwill (details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Goodwill by segment
Goodwill	$ 3,594	$ 3,611
Reportable Segments [Member] | Business and International Insurance [Member]
Goodwill by segment
Goodwill	2,459	2,476
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Goodwill by segment
Goodwill	495	495
Reportable Segments [Member] | Personal Insurance [Member]
Goodwill by segment
Goodwill	613	613
Other [Member]
Goodwill by segment
Goodwill	$ 27	$ 27