Consolidated Statements Of Operations and Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues
Net premiums written	$ 7,639	$ 4,784	$ 13,634	$ 8,860
Decrease (increase) in unearned premiums	(234)	(424)	368	(573)
Net premiums earned	7,405	4,360	14,002	8,287
Net investment income	708	562	1,382	1,113
Net realized gains (losses):
Other-than-temporary impairment (OTTI) losses gross	(16)	(14)	(87)	(27)
Portion of OTTI losses recognized in other comprehensive income (OCI)	0	6	8	6
Net OTTI losses recognized in income	(16)	(8)	(79)	(21)
Net realized gains (losses) excluding OTTI losses	(200)	134	(531)	58
Total net realized gains (losses) (includes $2, $34, $(150), and $31 reclassified from AOCI)	(216)	126	(610)	37
Total revenues	7,897	5,048	14,774	9,437
Expenses
Losses and loss expenses	4,254	2,417	7,928	4,539
Policy benefits	146	153	272	295
Policy acquisition costs	1,560	727	2,973	1,434
Administrative expenses	829	578	1,601	1,132
Interest expense	153	71	299	139
Other (income) expense	(29)	(38)	(1)	(73)
Amortization of purchased intangibles	5	55	12	85
Chubb integration expenses	98	0	246	0
Total expenses	7,016	3,963	13,330	7,551
Income before income tax	881	1,085	1,444	1,886
Income tax expense (includes $6, $10, $5 and $14 on reclassified unrealized gains and losses)	155	143	279	263
Net income	726	942	1,165	1,623
Other comprehensive income (loss)
Unrealized appreciation (depreciation)	947	(816)	1,852	(375)
Reclassification adjustment for net realized (gains) losses included in net income	(2)	(34)	150	(31)
Unrealized appreciation (Depreciation) after reclassification adjustment	945	(850)	2,002	(406)
Change in:
Cumulative translation adjustment	81	136	393	(285)
Pension liability	1	(6)	3	7
Other comprehensive income (loss), before income tax	1,027	(720)	2,398	(684)
Income tax (expense) benefit related to OCI items	(213)	175	(482)	100
Other comprehensive income (loss)	814	(545)	1,916	(584)
Comprehensive income	$ 1,540	$ 397	$ 3,081	$ 1,039
Earnings per share
Basic earnings per share	$ 1.55	$ 2.89	$ 2.55	$ 4.97
Diluted earnings per share	$ 1.54	$ 2.86	$ 2.53	$ 4.91