Unpaid losses and loss expenses Unpaid losses and loss expenses (Tables) - USD ($)
$ in Millions

3 Months Ended

Mar. 31, 2019

Mar. 31, 2018

Liability for Claims and Claims Adjustment Expense [Abstract]

Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block]

The following table presents a reconciliation of beginning and ending Unpaid losses and loss expenses:

	Three Months Ended March 31
(in millions of U.S. dollars)	2019			2018
Gross unpaid losses and loss expenses – beginning of period	$	62,960		$	63,179
Reinsurance recoverable on unpaid losses - beginning of period (1)	(14,689		)	(14,014		)
Net unpaid losses and loss expenses – beginning of period	48,271			49,165
Net losses and loss expenses incurred in respect of losses occurring in:
Current year	4,326			4,358
Prior years (2)	(228		)	(256		)
Total	4,098			4,102
Net losses and loss expenses paid in respect of losses occurring in:
Current year	785			809
Prior years	3,234			3,433
Total	4,019			4,242
Foreign currency revaluation and other	86			292
Net unpaid losses and loss expenses – end of period	48,436			49,317
Reinsurance recoverable on unpaid losses (1)	14,707			13,822
Gross unpaid losses and loss expenses – end of period	$	63,143		$	63,139

⁽¹⁾  Net of provision for uncollectible reinsurance.

⁽²⁾  Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments and earned premiums totaling $24 million and $47 million for the three months ended March 31, 2019 and 2018, respectively.

Prior Period Development, by Segment [Table Text Block]

	Three Months Ended March 31
(in millions of U.S. dollars)	Long-tail			Short-tail			Total
2019
North America Commercial P&C Insurance	$	(65	)	$	(66	)	$	(131	)
North America Personal P&C Insurance	—			(10		)	(10		)
North America Agricultural Insurance	—			(61		)	(61		)
Overseas General Insurance	—			(4		)	(4		)
Global Reinsurance	(1		)	(7		)	(8		)
Corporate	10			—			10
Total	$	(56	)	$	(148	)	$	(204	)
2018
North America Commercial P&C Insurance	$	8		$	(109	)	$	(101	)
North America Personal P&C Insurance	—			(6		)	(6		)
North America Agricultural Insurance	—			(76		)	(76		)
Overseas General Insurance	—			(22		)	(22		)
Global Reinsurance	—			(14		)	(14		)
Corporate	10			—			10
Total	$	18		$	(227	)	$	(209	)

Prior Year Claims and Claims Adjustment Expense

^[1]

$ (228)

$ (256)

[1] Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments and earned premiums totaling $24 million and $47 million for the three months ended March 31, 2019 and 2018, respectively.