Schedule II - Condensed Financial Information, Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating expenses:
Total operating expenses	$ 2,530	$ 2,321
Income before Income Taxes	890	819
Income tax expense (benefit)	297	305
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)	130	262
Shareholders' comprehensive income (loss)	$ 728	$ 781