Fair Value Measurements (Narrative) (Details) - USD ($)	9 Months Ended
May 31, 2020	May 31, 2019
Percentage of marketable securities investments mature within one year	67.00%
Percentage of marketable securities investments mature within one to three years	33.00%
Fair Value, Measurements, Nonrecurring [Member]
Assets fair value adjustments	$ 0	$ 0
Liabilities fair value adjustments	$ 0	$ 0

Amount of addition (reduction) to the amount at which a liability could be incurred (settled) in a current transaction between willing parties.

No definition available.

Name:	us-gaap_LiabilitiesFairValueAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration