Consolidated Statements of Earnings and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues
Net premiums earned	$ 1,253,515	$ 1,049,071	$ 3,736,596	$ 3,140,965
Net investment income	120,603	118,159	332,326	334,628
Net realized capital gains	27,221	29,202	117,126	158,513
Other than temporary impairment losses	(11,729)	(52,680)	(38,216)	(112,278)
Other revenue	225,006	45,285	527,765	125,270
Total revenues	1,614,616	1,189,037	4,675,597	3,647,098
Costs and Expenses
Net loss and loss adjustment expenses	718,556	594,729	2,198,512	1,737,100
Commissions, brokerage and other underwriting expenses	423,042	360,203	1,238,712	1,067,766
Other operating expenses	228,408	68,453	575,527	199,670
Corporate administration	10,745	10,922	33,938	33,441
Amortization of intangible assets	6,008	(1,104)	14,490	(3,815)
Interest expense	20,682	22,691	61,384	69,158
Total costs and expenses	1,407,441	1,055,894	4,122,563	3,103,320
Earnings (losses) before income taxes	207,175	133,143	553,034	543,778
Income taxes	48,328	36,045	162,274	138,113
Net earnings	158,847	97,098	390,760	405,665
Net earnings attributable to noncontrolling interest	3,016	568	3,353	1,448
Net earnings attributable to Alleghany stockholders	155,831	96,530	387,407	404,217
Net earnings	158,847	97,098	390,760	405,665
Other comprehensive income:
Change in unrealized gains (losses), net of deferred taxes	46,657	(150,904)	238,418	(198,689)
Less: reclassification for net realized capital gains and other than temporary impairment losses, net of taxes	(10,070)	15,261	(42,712)	(30,053)
Change in unrealized currency translation adjustment, net of deferred taxes	(3,041)	(386)	19,162	(8,253)
Retirement plans	95	129	452	(256)
Comprehensive income (loss)	192,488	(38,802)	606,080	168,414
Comprehensive income attributable to noncontrolling interest	3,016	568	3,353	1,448
Comprehensive income (loss) attributable to Alleghany stockholders	$ 189,472	$ (39,370)	$ 602,727	$ 166,966
Basic earnings per share attributable to Alleghany stockholders	$ 10.09	$ 6.07	$ 25.09	$ 25.31
Diluted earnings per share attributable to Alleghany stockholders	$ 10.09	$ 6.07	$ 25.08	$ 25.30