Acquisitions (Second Quarter 2016) - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($) Client
Savitz Organization [Member]
Business Acquisition, Contingent Consideration [Line Items]
Effective date of acquisition	Apr. 01, 2016
Acquired entity, name	Savitz Organization
Annual revenue	$ 20.0
Flex-Pay Business Services, Inc. [Member]
Business Acquisition, Contingent Consideration [Line Items]
Effective date of acquisition	Jun. 01, 2016
Acquired entity, name	Flex-Pay Business Services, Inc
Estimated revenue	$ 10.0
Flex-Pay Business Services, Inc. [Member] | Minimum [Member]
Business Acquisition, Contingent Consideration [Line Items]
Number of clients of acquired entity | Client	3,600