Consolidated Statements of Shareholders' Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement Of Comprehensive Income
Shareholders' Net Income	$ 598	$ 519
Shareholders' other comprehensive income (loss), net of tax:
Net unrealized appreciation (depreciation) on securities	7	173
Net unrealized appreciation (depreciation) on derivatives	(3)	(3)
Net translation of foreign currencies	112	81
Postretirement benefits liability adjustment	14	11
Shareholders' other comprehensive income (loss), net of tax	130	262
Shareholders' comprehensive income (loss)	$ 728	$ 781