Losses and Loss Expenses (Tables)

6 Months Ended

Jun. 30, 2018

Liability for Claims and Claims Adjustment Expense [Abstract]

Reconciliation of the beginning and ending balances of unpaid losses and loss expenses

The following table represents a reconciliation of the beginning and ending balances of unpaid losses and loss expenses, including an analysis of the Company's paid and unpaid losses and loss expenses incurred for the years indicated:

(U.S. dollars in thousands)	2018			2017
Unpaid losses and loss expenses at the beginning of the year	$	29,696,779		$	25,939,571
Unpaid losses and loss expenses recoverable at the beginning of the year (1)	7,239,446			5,480,300
Net unpaid losses and loss expenses at the beginning of the year	$	22,457,333		$	20,459,271
Increase (decrease) in net losses and loss expenses incurred in respect of losses occurring in:
Current year	3,361,365			3,175,267
Prior year	(18,050		)	(62,728		)
Total net incurred losses and loss expenses	$	3,343,315		$	3,112,539
Foreign exchange and other	(107,166		)	292,040
Less net losses and loss expenses paid in respect of losses occurring in:
Current year	277,656			343,934
Prior year	3,432,843			2,547,073
Total net paid losses	$	3,710,499		$	2,891,007
Net unpaid losses and loss expenses at June 30	21,982,983			20,972,843
Unpaid losses and loss expenses recoverable at June 30 (1)	7,198,164			5,849,503
Unpaid losses and loss expenses at June 30	$	29,181,147		$	26,822,346

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(1) P&C business only, net of provision for uncollectible reinsurance.

Segment Reporting Information [Line Items]

Net (favorable) adverse prior year loss development

The following table presents the net (favorable) adverse prior year loss development of the Company's loss and loss expense reserves for its P&C operations by operating segment for each of the years indicated:

	Six Months Ended
	June 30,
(U.S. dollars in thousands)	2018			2017
Insurance segment	$	46,588		$	(21,869	)
Reinsurance segment	(64,638		)	(40,859		)
Total	$	(18,050	)	$	(62,728	)

Insurance Segment

Segment Reporting Information [Line Items]

Net (favorable) adverse prior year loss development

The following table summarizes the net (favorable) adverse prior year reserve development by product type relating to the Insurance segment for the six months ended June 30, 2018 and 2017

	Six Months Ended
	June 30,
(U.S. dollars in thousands)	2018			2017
Professional	$	(3,016	)	$	(56,390	)
Casualty	(33,921		)	(81,985		)
Property	70,508			99,847
Specialty	13,017			16,659
Total	$	46,588		$	(21,869	)

Reinsurance Segment

Segment Reporting Information [Line Items]

Net (favorable) adverse prior year loss development

The following table summarizes the net (favorable) adverse prior year reserve development by line of business relating to the Reinsurance segment for the six months ended June 30, 2018 and 2017:

	Six Months Ended
	June 30,
(U.S. dollars in thousands)	2018			2017
Property and other short-tail lines	$	(62,883	)	$	(110,025	)
Casualty and other long-tail lines	(1,755		)	69,166
Total	$	(64,638	)	$	(40,859	)