Stockholders' Equity (Narratives) (Details) (USD $)	0 Months Ended	3 Months Ended				6 Months Ended
	Jan. 29, 2013	May 31, 2013	Feb. 28, 2013	May 31, 2012	Feb. 29, 2012	May 31, 2013	May 31, 2012
Equity [Abstract]
Stock issued during period, shares	6,325,000
Common stock, par value per share		$ 1.00				$ 1.00
Treasury stock acquired, average cost per share	$ 18.25
Stock issued during period, shares, treasury stock reissued	6,325,000
Proceeds from issuance of common stock, net	$ 109,500,000					$ 109,503,000	$ 0
Common stock reserve, shares		12,602,735				12,602,735
Number of common stock, authorized, approved under a board approved stock repurchase program		4,000,000				4,000,000
Dividend paid in each quarter (in dollars per share)		$ 0.0250	$ 0.0250	$ 0.0250	$ 0.0625	$ 0.0500	$ 0.0875
Convertible senior notes due February 1, 2019 at 1.375%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 230,000,000