Acquisitions (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Recognized amounts of identifiable assets acquired and liabilities assumed:
Goodwill	$ 62,900	$ 16,900	$ 34,000
Meridian Insurance Group, LLC (Meridian), Primarily Care, Inc. (PCI) Stoltz and Company, LTD., L.L.P (Stoltz), Trinity Risk Advisors, Inc.(Trinity), Strategic Employee Benefit Services-The Pruett Group, Inc. (SEBS-Pruett), ProMedical, Inc. (ProMedical), the employee benefit division of Leavitt Pacific Insurance Brokers, Inc. (Leavitt), Diversified Industries, Inc. d/b/a Payroll Control Systems (PCS) and PHBV Partners, L.L.P. (PHBV) [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed:
Cash	422
Funds held for clients	39,193
Accounts receivable, net	8,275
Fixed assets and other	690
Identifiable intangible assets	42,372
Accrued liabilities	(5,393)
Client fund obligations	(39,193)
Deferred tax liability	(1,236)
Total identifiable net assets	45,130
Goodwill	62,931
Aggregate purchase price	108,061
Thompson Dunavant PLC, Multiple Benefit Services, Inc. (MBS), Gresham Smith LLC and Atlantic MDR, LLC (d/b/a Advantage Benefit Planning) (ABP) [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed:
Cash		273
Accounts receivable, net		3,606
Fixed assets and other		437
Identifiable intangible assets		11,072
Accrued liabilities		(924)
Deferred tax liability		(1,775)
Total identifiable net assets		12,689
Goodwill		16,869
Aggregate purchase price		29,558
Goldstein Lewin & Company, National Benefit Alliance, South Winds, Inc. (d/b/a Benexx) and Kirkland, Russ, Murphy & Tapp [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed:
Accounts receivable, net			1,294
Prepaid expenses and other current assets			1,430
Fixed assets and other			1,659
Identifiable intangible assets			11,550
Accrued liabilities			(303)
Total identifiable net assets			15,630
Goodwill			33,986
Aggregate purchase price			$ 49,616