Acquisitions (First Quarter 2015) - Additional Information (Detail) $ in Millions			3 Months Ended
	Jan. 01, 2016 USD ($)	Mar. 01, 2015	Mar. 31, 2016 USD ($) Client_List Business	Mar. 31, 2015 USD ($) Client_List Business
Series of Business Acquisition First Quarter 2016 [Member]
Business Acquisition, Contingent Consideration [Line Items]
Consideration paid in cash			$ 1.3
Number of businesses acquired | Business			1
Contingent consideration			$ 1.9
Guaranteed future consideration			$ 1.0
Series of Business Acquisition First Quarter 2016 [Member] | Employee Services [Member]
Business Acquisition, Contingent Consideration [Line Items]
Number of client list purchased | Client_List			2
Millimaki Eggert, L.L.P [Member]
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration			$ 1.2
Annual revenue	$ 2.4
Acquired entity, name			Millimaki Eggert, L.L.P.
Effective date of acquisition			Jan. 01, 2016
Series of Business Acquisition First Quarter 2015 [Member]
Business Acquisition, Contingent Consideration [Line Items]
Consideration paid in cash				$ 5.6
Number of businesses acquired | Business				1
Contingent consideration				$ 4.5
Series of Business Acquisition First Quarter 2015 [Member] | Employee Services [Member]
Business Acquisition, Contingent Consideration [Line Items]
Number of client list purchased | Client_List				2
Model Consulting, Inc [Member]
Business Acquisition, Contingent Consideration [Line Items]
Acquired entity, name		Model Consulting, Inc.
Effective date of acquisition				Mar. 01, 2015