Unaudited Consolidated Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Revenues
Net premiums written	$ 1,064,990		$ 952,776
Change in unearned premiums	(205,210)		(200,006)
Net premiums earned	859,780		752,770
Net investment income	66,994		65,672
Net realized gains	19,697		58,340
Other-than-temporary impairment losses	(2,971)		(2,248)
Less investment impairments recognized in other comprehensive income, before taxes	0		2
Net impairment losses recognized in earnings	(2,971)		(2,246)
Other underwriting income	1,582		538
Equity in net income of investment funds accounted for using the equity method	3,253		13,823
Other income (loss)	(2,104)		1,244
Total revenues	946,231		890,141
Expenses
Losses and loss adjustment expenses	436,240		399,403
Acquisition expenses	160,342		127,592
Other operating expenses	145,799		120,183
Interest expense	14,404		5,898
Net foreign exchange losses (gains)	6,563		(24,264)
Total expenses	763,348		628,812
Income before income taxes	182,883		261,329
Income tax expense	3,738		4,853
Net income	179,145		256,476
Net (income) loss attributable to noncontrolling interests	3,355	[1]	0	[1]
Net income available to Arch	182,500		256,476
Preferred dividends	5,484		5,484
Net income available to common shareholders	$ 177,016		$ 250,992
Net income per common share
Basic (per share)	$ 1.34		$ 1.92
Diluted (per share)	$ 1.30		$ 1.85
Weighted average common shares and common share equivalents outstanding
Basic (shares)	131,857,910		130,907,902
Diluted (shares)	136,562,717		135,409,288

[1] See Note 4.