Fair Value Measurements (Details) - Recurring basis - USD ($) $ in Thousands	May 31, 2017	Aug. 31, 2016
Fair value measurements
Restricted investments	$ 1,949	$ 1,637
Long-term debt	20,000	43,400
Quoted prices in active markets (Level 1)
Fair value measurements
Restricted investments	1,906	1,610
Significant other observable inputs (Level 2)
Fair value measurements
Restricted investments	43	27
Long-term debt	$ 20,000	$ 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