Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt (Details 4) (USD $)	May 31, 2014	May 31, 2014 Credit Agreement	Jun. 11, 2014 Credit Agreement Subsequent event	May 31, 2014 3.90% unsecured Senior Notes payable Fair value	Feb. 28, 2014 3.90% unsecured Senior Notes payable Fair value	May 31, 2014 3.90% unsecured Senior Notes payable Fair value Fair Value, Level 2	Feb. 28, 2014 3.90% unsecured Senior Notes payable Fair value Fair Value, Level 2	May 31, 2014 3.90% unsecured Senior Notes payable Fair value Fair Value, Level 2 Discounted cash flow analysis	May 31, 2014 3.90% unsecured Senior Notes payable Book value
Long-term debt
Long-term debt				$ 83,866,000	$ 83,951,000	$ 83,866,000	$ 83,951,000	$ 83,870,000	$ 80,000,000
Unsecured revolving commitment		375,000,000	570,000,000
Limit on additional debt borrowings	$ 150,840,000