Service Revenue (Narrative) (Details)	3 Months Ended
Aug. 31, 2018
Service Revenue [Abstract]
Percentage of client worksite employees participation in benefit plans not retained risk	60.00%
Percentage of client worksite employees participation in benefit plans retained risk	40.00%
Revenue performance obligations timing	the Company defers revenue associated with these performance obligations, which exceed one year, and subsequently recognizes these as future services are provided, over approximately three to four years

Description of timing for satisfying performance obligation in contract with customer. Includes, but is not limited to, as services are rendered, and upon shipment, delivery or completion of service.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130554-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration