Consolidated Statements Of Operations and Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Net premiums written	$ 8,622	$ 8,110	$ 24,278	$ 23,229
Increase in unearned premiums	(295)	(202)	(923)	(630)
Net premiums earned	8,327	7,908	23,355	22,599
Net investment income	873	823	2,568	2,457
Net realized gains (losses):
Other-than-temporary impairment (OTTI) losses gross	(54)	(14)	(81)	(19)
Portion of OTTI losses recognized in other comprehensive income (OCI)	30	3	31	3
Net OTTI losses recognized in income	(24)	(11)	(50)	(16)
Net realized gains (losses) excluding OTTI losses	(131)	30	(425)	51
Net Realized Gains Losses	(155)	19	(475)	35
Total revenues	9,045	8,750	25,448	25,091
Expenses
Losses and loss expenses	5,052	4,868	13,865	13,457
Policy benefits	158	127	515	428
Policy acquisition costs	1,603	1,504	4,611	4,432
Administrative expenses	752	719	2,220	2,158
Interest expense	138	164	418	488
Other (income) expense	(57)	(145)	(326)	(307)
Amortization of purchased intangibles	76	83	229	253
Chubb integration expenses	2	16	9	39
Total expenses	7,724	7,336	21,541	20,948
Income before income tax	1,321	1,414	3,907	4,143
Income tax expense (benefit) (includes nil, $(4), $(2) and $(19) on reclassified unrealized gains and losses)	230	183	626	536
Net income	1,091	1,231	3,281	3,607
Other comprehensive income (loss)
Unrealized appreciation (depreciation)	694	(251)	3,791	(2,063)
Reclassification adjustment for net realized (gains) losses included in net income	11	38	43	142
Unrealized appreciation (Depreciation) after reclassification adjustment	705	(213)	3,834	(1,921)
Change in:
Cumulative foreign currency translation adjustment	(193)	(482)	(143)	(659)
Postretirement benefit liability adjustment	(17)	(21)	(62)	(61)
Other comprehensive income (loss), before income tax	495	(716)	3,629	(2,641)
Income tax (expense) benefit related to OCI items	(113)	77	(660)	356
Other comprehensive income (loss)	382	(639)	2,969	(2,285)
Comprehensive income	$ 1,473	$ 592	$ 6,250	$ 1,322
Earnings per share
Basic earnings per share	$ 2.40	$ 2.66	$ 7.18	$ 7.76
Diluted earnings per share	$ 2.38	$ 2.64	$ 7.13	$ 7.71