Derivative Financial Instruments and Hedging Activities Pretax Gains losses reclassified from OCI (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Feb. 28, 2017	Feb. 29, 2016	Feb. 28, 2017	Feb. 29, 2016
Interest Expense
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest rate derivatives	$ (436)	$ (275)	$ (877)	$ (465)

The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

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