Goodwill and Other Intangibles - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Aug. 31, 2018	Aug. 31, 2017	May 31, 2016
Goodwill and Other Intangibles (Details) [Line Items]
Amortizable intangible assets acquired	$ 0.5	$ 0.1	$ 3.3
Amortization expense	$ 0.7	$ 0.5	$ 2.1
Useful life	4 years
U.K. Based Book Business [Member]
Goodwill and Other Intangibles (Details) [Line Items]
Amortizable intangible assets acquired	$ 0.5

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

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