Segment Information (Tables)

6 Months Ended

Jun. 30, 2024

Segment Reporting [Abstract]

Analysis of underwriting income or loss by segment and reconciliation to net income available to common shareholders

The following tables summarize the Company’s underwriting income or loss by segment, together with a reconciliation of underwriting income or loss to net income available to Arch common shareholders:

	Three Months Ended
	June 30, 2024
	Insurance			Reinsurance			Mortgage			Total
Gross premiums written (1)	$	2,102		$	2,941		$	340		$	5,382
Premiums ceded (1)	(544)			(994)			(64)			(1,601)
Net premiums written	1,558			1,947			276			3,781
Change in unearned premiums	(80)			(167)			31			(216)
Net premiums earned	1,478			1,780			307			3,565
Other underwriting income (loss)	—			1			2			3
Losses and loss adjustment expenses	(848)			(1,006)			27			(1,827)
Acquisition expenses	(288)			(345)			—			(633)
Other operating expenses	(233)			(64)			(49)			(346)
Underwriting income (loss)	$	109		$	366		$	287		762
Net investment income										364
Net realized gains (losses)										122
Equity in net income (loss) of investment funds accounted for using the equity method										167
Other income (loss)										8
Corporate expenses (2)										(23)
Transaction costs and other (2)										(18)
Amortization of intangible assets										(27)
Interest expense										(35)
Net foreign exchange gains (losses)										1
Income (loss) before income taxes and income (loss) from operating affiliates										1,321
Income tax (expense) benefit										(97)
Income (loss) from operating affiliates										45
Net income (loss) available to Arch										1,269
Preferred dividends										(10)
Net income (loss) available to Arch common shareholders										$	1,259
Underwriting Ratios
Loss ratio	57.3		%	56.5		%	(8.6)		%	51.2		%
Acquisition expense ratio	19.5		%	19.4		%	0.1		%	17.8		%
Other operating expense ratio	15.8		%	3.6		%	15.9		%	9.7		%
Combined ratio	92.6		%	79.5		%	7.4		%	78.7		%
Goodwill and intangible assets	$	255		$	114		$	356		$	725

(1)    Certain assumed and ceded amounts related to intersegment transactions are included in individual segment results. Accordingly, the sum of such transactions for each segment does not agree to the total due to eliminations.

(2)    Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’

	Three Months Ended
	June 30, 2023
	Insurance			Reinsurance			Mortgage			Total
Gross premiums written (1)	$	1,955		$	2,544		$	347		$	4,845
Premiums ceded (1)	(501)			(835)			(82)			(1,417)
Net premiums written	1,454			1,709			265			3,428
Change in unearned premiums	(126)			(366)			29			(463)
Net premiums earned	1,328			1,343			294			2,965
Other underwriting income (loss)	—			3			3			6
Losses and loss adjustment expenses	(761)			(743)			13			(1,491)
Acquisition expenses	(264)			(290)			(7)			(561)
Other operating expenses	(195)			(68)			(50)			(313)
Underwriting income (loss)	$	108		$	245		$	253		606
Net investment income										242
Net realized gains (losses)										(123)
Equity in net income (loss) of investment funds accounted for using the equity method										69
Other income (loss)										3
Corporate expenses (2)										(20)
Transaction costs and other (2)										(1)
Amortization of intangible assets										(24)
Interest expense										(33)
Net foreign exchange gains (losses)										(5)
Income (loss) before income taxes and income (loss) from operating affiliates										714
Income tax (expense) benefit										(67)
Income (loss) from operating affiliates										22
Net income (loss)										669
Net (income) loss attributable to noncontrolling interests										2
Net income (loss) available to Arch										671
Preferred dividends										(10)
Net income (loss) available to Arch common shareholders										$	661
Underwriting Ratios
Loss ratio	57.3		%	55.3		%	(4.5)		%	50.3		%
Acquisition expense ratio	19.9		%	21.6		%	2.4		%	18.9		%
Other operating expense ratio	14.7		%	5.0		%	17.1		%	10.6		%
Combined ratio	91.9		%	81.9		%	15.0		%	79.8		%
Goodwill and intangible assets	$	228		$	146		$	401		$	775

(1)    Certain assumed and ceded amounts related to intersegment transactions are included in individual segment results. Accordingly, the sum of such transactions for each segment does not agree to the total due to eliminations.

(2)    Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’

	Six Months Ended
	June 30, 2024
	Insurance			Reinsurance			Mortgage			Total
Gross premiums written (1)	$	4,228		$	6,408		$	681		$	11,315
Premiums ceded (1)	(1,128)			(2,195)			(128)			(3,449)
Net premiums written	3,100			4,213			553			7,866
Change in unearned premiums	(171)			(767)			59			(879)
Net premiums earned	2,929			3,446			612			6,987
Other underwriting income (loss)	—			3			12			15
Losses and loss adjustment expenses	(1,702)			(1,889)			36			(3,555)
Acquisition expenses	(564)			(676)			—			(1,240)
Other operating expenses	(468)			(139)			(102)			(709)
Underwriting income (loss)	$	195		$	745		$	558		1,498
Net investment income										691
Net realized gains (losses)										189
Equity in net income (loss) of investment funds accounted for using the equity method										266
Other income (loss)										22
Corporate expenses (2)										(69)
Transaction costs and other (2)										(25)
Amortization of intangible assets										(48)
Interest expense										(69)
Net foreign exchange gains (losses)										32
Income (loss) before income taxes and income (loss) from operating affiliates										2,487
Income tax (expense) benefit										(198)
Income (loss) from operating affiliates										100
Net income (loss) available to Arch										2,389
Preferred dividends										(20)
Net income (loss) available to Arch common shareholders										$	2,369
Underwriting Ratios
Loss ratio	58.1		%	54.8		%	(5.8)		%	50.9		%
Acquisition expense ratio	19.2		%	19.6		%	0.1		%	17.7		%
Other operating expense ratio	16.0		%	4.0		%	16.7		%	10.1		%
Combined ratio	93.3		%	78.4		%	11.0		%	78.7		%

(1)    Certain assumed and ceded amounts related to intersegment transactions are included in individual segment results. Accordingly, the sum of such transactions for each segment does not agree to the total due to eliminations.

(2)    Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’

	Six Months Ended
	June 30, 2023
	Insurance			Reinsurance			Mortgage			Total
Gross premiums written (1)	$	3,934		$	5,004		$	690		$	9,625
Premiums ceded (1)	(1,043)			(1,569)			(164)			(2,773)
Net premiums written	2,891			3,435			526			6,852
Change in unearned premiums	(306)			(762)			64			(1,004)
Net premiums earned	2,585			2,673			590			5,848
Other underwriting income (loss)	—			7			9			16
Losses and loss adjustment expenses	(1,464)			(1,509)			11			(2,962)
Acquisition expenses	(509)			(571)			(14)			(1,094)
Other operating expenses	(390)			(142)			(100)			(632)
Underwriting income (loss)	$	222		$	458		$	496		1,176
Net investment income										441
Net realized gains (losses)										(106)
Equity in net income (loss) of investment funds accounted for using the equity method										117
Other income (loss)										14
Corporate expenses (2)										(49)
Transaction costs and other (2)										(2)
Amortization of intangible assets										(47)
Interest expense										(65)
Net foreign exchange gains (losses)										(23)
Income (loss) before income taxes and income (loss) from operating affiliates										1,456
Income tax (expense) benefit										(131)
Income (loss) from operating affiliates										61
Net income (loss) available to Arch										1,386
Preferred dividends										(20)
Net income (loss) available to Arch common shareholders										$	1,366
Underwriting Ratios
Loss ratio	56.6		%	56.5		%	(1.9)		%	50.6		%
Acquisition expense ratio	19.7		%	21.3		%	2.4		%	18.7		%
Other operating expense ratio	15.1		%	5.3		%	17.0		%	10.8		%
Combined ratio	91.4		%	83.1		%	17.5		%	80.1		%

(1)    Certain assumed and ceded amounts related to intersegment transactions are included in individual segment results. Accordingly, the sum of such transactions for each segment does not agree to the total due to eliminations.

(2)    Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’