Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Available-for-sale securities at fair value:
Equity securities (cost: 2014 - $2,265,027; 2013 - $1,804,698)	$ 2,637,802	$ 2,229,453
Debt securities (amortized cost: 2014 - $14,682,684; 2013 - $14,875,750)	14,802,122	14,802,890
Short-term investments	926,674	1,317,895
Marketable Securities, Total	18,366,598	18,350,238
Other invested assets	619,674	641,924
Total investments	18,986,272	18,992,162
Cash	481,414	498,315
Accrued investment income	141,820	146,381
Premium balances receivable	788,260	675,255
Reinsurance recoverables	1,354,229	1,363,707
Ceded unearned premiums	185,159	173,148
Deferred acquisition costs	358,398	334,740
Property and equipment at cost, net of accumulated depreciation and amortization	67,777	58,974
Goodwill	99,747	99,747
Intangible assets, net of amortization	129,145	127,284
Current taxes receivable	25,644	13,049
Net deferred tax assets	412,697	469,787
Other assets	463,774	408,539
Total assets	23,494,336	23,361,088
Liabilities and Stockholders' Equity
Loss and loss adjustment expenses	11,864,719	11,952,541
Unearned premiums	1,857,948	1,765,550
Senior Notes	1,790,041	1,794,407
Reinsurance payable	107,402	90,562
Other liabilities	736,147	810,507
Total liabilities	16,356,257	16,413,567
Common stock (shares authorized: 2014 and 2013 - 22,000,000; shares issued: 2014 -17,459,961; 2013 - 17,459,961)	17,460	17,460
Contributed capital	3,611,300	3,613,151
Accumulated other comprehensive income	279,049	186,930
Treasury stock, at cost (2014 - 924,370 shares; 2013 - 693,769 shares)	(304,760)	(213,911)
Retained earnings	3,525,007	3,320,127
Total stockholders' equity attributable to Alleghany stockholders	7,128,056	6,923,757
Noncontrolling interest	10,023	23,764
Total stockholders' equity	7,138,079	6,947,521
Total liabilities and stockholders' equity	$ 23,494,336	$ 23,361,088