Acquisitions - Allocated Aggregate Purchase Price of Acquisitions (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill	$ 410,539	$ 384,697
Centric Insurance Agency (Centric), Clearview National Partners, LLC (Clearview) and Lewis Birch & Richardo, LLC (LBR) [Member]
Business Acquisition [Line Items]
Cash	402
Accounts receivable	3,416
Work in process	900
Other assets	488
Identifiable intangible assets	10,283
Current liabilities	(2,342)
Total identifiable net assets	13,147
Goodwill	26,325
Aggregate purchase price	$ 39,472

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Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of other assets expected to be realized or consumed before one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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