Consolidated Statements Of Operations and Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Net premiums written	$ 17,713	$ 17,799	$ 17,025
Increase in unearned premiums	(500)	(373)	(412)
Net premiums earned	17,213	17,426	16,613
Net investment income	2,194	2,252	2,144
Net realized gains (losses):
Other-than-temporary impairment (OTTI) losses gross	(151)	(75)	(22)
Portion of OTTI losses recognized in other comprehensive income (OCI)	(39)	(7)
Net OTTI losses recognized in income	(112)	(68)	(22)
Net realized gains (losses) excluding OTTI losses	(308)	(439)	526
Total net realized gains (losses)	(420)	(507)	504
Total revenues	18,987	19,171	19,261
Expenses
Losses and loss expenses	9,484	9,649	9,348
Policy benefits	543	517	515
Policy acquisition costs	2,941	3,075	2,659
Administrative expenses	2,270	2,245	2,211
Interest expense	300	280	275
Other (income) expense	(51)	(190)	(80)
Amortization of Intangible Assets	171	108	95
Chubb integration expenses	33	0	0
Total expenses	15,691	15,684	15,023
Income before income tax	3,296	3,487	4,238
Income tax expense	462	634	480
Net income	2,834	2,853	3,758
Other comprehensive income (loss)
Unrealized appreciation (depreciation)	(1,280)	820	(1,762)
Reclassification adjustment for net realized (gains) losses included in net income	151	24	(105)
Other comprehensive income (loss)after reclassification for net realized gains included in net income	(1,129)	844	(1,867)
Change in:
Cumulative translation adjustment	(958)	(632)	(339)
Pension liability	15	2
Other comprehensive income (loss), before income tax	(2,072)	214	(2,206)
Income tax benefit (expense) related to OCI items	146	(175)	471
Other comprehensive income (loss)	(1,926)	39	(1,735)
Comprehensive income	$ 908	$ 2,892	$ 2,023
Earnings per share
Basic earnings per share	$ 8.71	$ 8.50	$ 11.02
Diluted earnings per share	$ 8.62	$ 8.42	$ 10.92