Condensed Unaudited Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Schedule of quarterly financial information

	Three Months Ended
	March 31			June 30			September 30		December 31
(in millions of U.S. dollars, except per share data)	2016			2016			2016		2016
Net premiums earned	$	6,597		$	7,405		$	7,688	$	7,059
Net investment income	674			708			739		744
Net realized gains (losses) including OTTI	(394		)	(216		)	100		365
Total revenues	$	6,877		$	7,897		$	8,527	$	8,168
Losses and loss expenses	$	3,674		$	4,254		$	4,269	$	3,855
Policy benefits	$	126		$	146		$	155	$	161
Net income	$	439		$	726		$	1,360	$	1,610
Basic earnings per share	$	0.98		$	1.55		$	2.90	$	3.44
Diluted earnings per share	$	0.97		$	1.54		$	2.88	$	3.41

	Three Months Ended
	March 31			June 30		September 30			December 31
(in millions of U.S. dollars, except per share data)	2015			2015		2015			2015
Net premiums earned	$	3,927		$	4,360	$	4,719		$	4,207
Net investment income	551			562		549			532
Net realized gains (losses) including OTTI	(89		)	126		(397		)	(60		)
Total revenues	$	4,389		$	5,048	$	4,871		$	4,679
Losses and loss expenses	$	2,122		$	2,417	$	2,643		$	2,302
Policy benefits	$	142		$	153	$	89		$	159
Net income	$	681		$	942	$	528		$	683
Basic earnings per share	$	2.08		$	2.89	$	1.63		$	2.10
Diluted earnings per share	$	2.05		$	2.86	$	1.62		$	2.08