Acquisitions (First quarter 2014) - Additional Information (Detail) $ in Millions			3 Months Ended			6 Months Ended
	Feb. 01, 2014	Jan. 01, 2014 Employees	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($) Business	Mar. 31, 2014 USD ($) Business	Jun. 30, 2015 USD ($)
Business Acquisition, Contingent Consideration [Line Items]
Consideration paid in common stock			$ 0.3			$ 0.8
Contingent consideration			$ 4.2			$ 4.2
Clearview National Partners, L.L.C, Centric Insurance Agency and Lewis Birch & Richardo, LLC [Member]
Business Acquisition, Contingent Consideration [Line Items]
Consideration paid in cash				$ 8.1	$ 16.5
Consideration paid in common stock				0.9	1.9
Contingent consideration				$ 2.1	$ 10.2
Number of businesses acquired | Business				1	3
Centric Insurance Agency [Member]
Business Acquisition, Contingent Consideration [Line Items]
Acquired entity, name		Centric Insurance Agency
Effective date of acquisition						Jan. 01, 2014
Lewis Birch & Richardo, LLC [Member]
Business Acquisition, Contingent Consideration [Line Items]
Acquired entity, name	Lewis Birch & Richardo, LLC
Effective date of acquisition						Feb. 01, 2014
Clearview National Partners, L.L.C [Member]
Business Acquisition, Contingent Consideration [Line Items]
Acquired entity, name		Clearview National Partners, LLC
Effective date of acquisition						Jan. 01, 2014
Clearview National Partners, L.L.C [Member] | Minimum [Member]
Business Acquisition, Contingent Consideration [Line Items]
Number of employees covered | Employees		100