Consolidated Statements of Earnings and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenues
Net premiums earned	$ 1,053,997	$ 1,075,013
Net investment income	110,583	118,811
Net realized capital gains	96,836	50,902
Other than temporary impairment losses	(5,220)	(32,312)
Other income	30,446	11,141
Total revenues	1,286,642	1,223,555
Costs and Expenses
Net loss and loss adjustment expenses	611,159	567,413
Commissions, brokerage and other underwriting expenses	324,236	326,227
Other operating expenses	53,342	30,738
Corporate administration	9,632	12,422
Amortization of intangible assets	(1,861)	11,630
Interest expense	21,811	21,736
Total costs and expenses	1,018,319	970,166
Earnings before income taxes	268,323	253,389
Income taxes	63,682	57,095
Net earnings	204,641	196,294
Net losses attributable to noncontrolling interest	(239)
Net earnings attributable to Alleghany stockholders	204,880	196,294
Net earnings	204,641	196,294
Other comprehensive income:
Change in unrealized gains, net of deferred taxes of $81,364 and $45,877 for 2014 and 2013, respectively	151,104	85,200
Less: reclassification for net realized capital gains and other than temporary impairment losses, net of taxes of ($32,066) and ($6,507) for 2014 and 2013, respectively	(59,550)	(12,084)
Change in unrealized currency translation adjustment, net of deferred taxes of $233 and ($5,366) for 2014 and 2013, respectively	432	(9,966)
Retirement plans	133	(154)
Comprehensive income	296,760	259,290
Comprehensive loss attributable to noncontrolling interest	(239)
Comprehensive income attributable to Alleghany stockholders	$ 296,999	$ 259,290
Basic earnings per share attributable to Alleghany stockholders	$ 12.28	$ 11.67
Diluted earnings per share attributable to Alleghany stockholders	$ 12.28	$ 11.67