Condensed Unaudited Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2017

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)	2017			2017		2017			2017
Net premiums earned	$	6,772		$	7,237	$	7,807		$	7,218
Net investment income	745			770		813			797
Net realized gains (losses) including OTTI	(7		)	101		(10		)	—
Total revenues	$	7,510		$	8,108	$	8,610		$	8,015
Losses and loss expenses	$	3,789		$	4,146	$	6,247		$	4,272
Policy benefits	$	168		$	163	$	169		$	176
Net income (loss)	$	1,093		$	1,305	$	(70	)	$	1,533
Basic earnings (loss) per share	$	2.33		$	2.79	$	(0.15	)	$	3.29
Diluted earnings (loss) per share	$	2.31		$	2.77	$	(0.15	)	$	3.27

Net income for the three months ended September 30, 2017 included after-tax catastrophe losses of $1.5 billion. Net income for the three months ended December 31, 2017 included a one-time income tax transition benefit of $450 million related to the 2017 Tax Act. Refer to Note 8 for additional 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