Fair Value Measurements (Details) - Recurring basis - USD ($) $ in Thousands	Aug. 31, 2017	Aug. 31, 2016
Fair value measurements
Restricted investments	$ 964	$ 1,637
Long-term debt		43,400
Quoted prices in active markets (Level 1)
Fair value measurements
Restricted investments	926	1,610
Significant other observable inputs (Level 2)
Fair value measurements
Restricted investments	$ 38	27
Long-term debt		$ 43,400

The aggregate value of all restricted investments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-12C.9(c))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-12.6(c))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010

Name:	us-gaap_RestrictedInvestmentsAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant