Long Lived Assets and Total Assets of Business Segments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Property and equipment, net	$ 72,711	$ 61,553
Goodwill and intangible assets	417,113	314,616
Total assets	6,766,034	5,678,747
Small Commercial Business
Segment Reporting Information [Line Items]
Property and equipment, net	25,397	17,767
Goodwill and intangible assets	179,775	123,976
Total assets	2,577,354	2,150,824
Specialty Risk and Extended Warranty
Segment Reporting Information [Line Items]
Property and equipment, net	28,232	30,811
Goodwill and intangible assets	214,886	167,782
Total assets	2,778,836	2,482,018
Specialty Program
Segment Reporting Information [Line Items]
Property and equipment, net	15,781	10,762
Goodwill and intangible assets	22,452	22,858
Total assets	1,234,582	912,476
Personal Lines Reinsurance
Segment Reporting Information [Line Items]
Property and equipment, net	3,301	2,213
Goodwill and intangible assets	0	0
Total assets	175,262	133,429
Corporate and Other
Segment Reporting Information [Line Items]
Property and equipment, net	0	0
Total assets	$ 0	$ 0

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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