Business Combinations (Acquisitions Accounted For As Business Combinations) (Details) (USD $) In Thousands, unless otherwise specified									3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2011 Balcos Insurance, Inc., Et Al [Member]	Mar. 31, 2011 Associated Insurance Service, Inc., Et Al [Member]	Mar. 31, 2012 Arrowhead General Insurance Agency Superholding Corporation [Member]	Mar. 31, 2011 United Benefit Services Insurance Agency, Et Al [Member]	Mar. 31, 2012 Other [Member]	Mar. 31, 2011 Other [Member]	Mar. 31, 2011 Retail [Member] Balcos Insurance, Inc., Et Al [Member]	Mar. 31, 2011 Retail [Member] Associated Insurance Service, Inc., Et Al [Member]	Mar. 31, 2011 Retail [Member] United Benefit Services Insurance Agency, Et Al [Member]	Mar. 31, 2011 Retail [Member] Other [Member]	Mar. 31, 2012 Various [Member] Other [Member]	Mar. 31, 2012 National Programs & Services [Member] Arrowhead General Insurance Agency Superholding Corporation [Member]
Business Acquisition [Line Items]
Date of Acquisition									January 1	January 1	February 1	Various	Various	January 9
Cash Paid	$ 401,247	$ 43,855							$ 8,611	$ 12,000	$ 14,283	$ 8,961	$ 3,716	$ 397,531
Note Payable		550										550
Other Payable	21,391													21,391
Recorded Earn-out Payable	4,714	8,941							1,595	1,575	3,199	2,572	1,080	3,634
Net Assets Acquired	427,352	53,346	10,206	13,575	422,556	17,482	4,796	12,083	10,206	13,575	17,482	12,083	4,796	422,556
Maximum Potential Earn-out Payable	$ 8,488	$ 27,762							$ 5,766	$ 6,000	$ 9,133	$ 6,863	$ 3,488	$ 5,000