Consolidated Statements of Shareholders' Comprehensive Income (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Statement Of Comprehensive Income [Abstract]    
Shareholders' Net Income $ 533 $ 528
Shareholders' other comprehensive income (loss):    
Net unrealized appreciation (depreciation) on securities 88 86
Net unrealized appreciation (depreciation), derivatives 7 0
Net translation of foreign currencies (104) (11)
Postretirement benefits liability adjustment 11 12
Shareholders' other comprehensive income (loss) 2 87
Shareholders' comprehensive income (loss) $ 535 $ 615