Unaudited Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues
Net premiums written	$ 2,137,246	$ 1,525,259
Change in unearned premiums	(392,802)	(156,393)
Net premiums earned	1,744,444	1,368,866
Net investment income	145,153	156,949
Net realized gains (losses)	(366,960)	140,256
Other underwriting income	6,852	8,825
Equity in net income (loss) of investment funds accounted for using the equity method	(4,209)	46,867
Other income	8,548	1,083
Total revenues	1,533,828	1,722,846
Expenses
Losses and loss adjustment expenses	1,115,419	718,532
Acquisition expenses	247,283	197,848
Other operating expenses	234,544	201,163
Corporate expenses	20,796	17,962
Amortization of intangible assets	16,631	20,417
Interest expense	32,555	29,065
Net foreign exchange (gains) losses	(72,671)	(3,525)
Total expenses	1,594,557	1,181,462
Income (loss) before income taxes	(60,729)	541,384
Income tax expense	(27,945)	(45,886)
Net income (loss)	(88,674)	495,498
Net (income) loss attributable to noncontrolling interests	232,791	(46,970)
Net income available to Arch	144,117	448,528
Preferred dividends	(10,403)	(10,403)
Net income available to Arch common shareholders	$ 133,714	$ 438,125
Net income per common share and common share equivalent
Basic (per share)	$ 0.33	$ 1.09
Diluted (per share)	$ 0.32	$ 1.07
Weighted average common shares and common share equivalents outstanding
Basic (shares)	403,892,161	400,184,404
Diluted (shares)	414,033,570	408,971,029