Consolidated Statements of Shareholders' Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement Of Comprehensive Income
Shareholders' Net Income	$ 915	$ 598
Shareholders' other comprehensive income (loss), net of tax:
Net unrealized appreciation (depreciation) on securities	(279)	7
Net unrealized appreciation (depreciation) on derivatives	(5)	(3)
Net translation of foreign currencies	45	112
Postretirement benefits liability adjustment	13	14
Shareholders' other comprehensive income (loss), net of tax	(226)	130
Shareholders' comprehensive income (loss)	$ 689	$ 728