Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2015	May. 31, 2014
Class of Stock [Line Items]
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			1,595,910
Net income (loss)	$ 9,573	$ 26,624	17,372	$ 37,187
Dividends on common stock			(4,599)
Stock-based compensation			7,428
Treasury Stock, Value, Acquired, Cost Method			(300)
Ending balance	1,615,836		1,615,836
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			$ 25
Common Stock
Class of Stock [Line Items]
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures			80
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 115,387
Ending balance	115,469		115,469
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			2
Paid-in Capital
Class of Stock [Line Items]
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			(80)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			668,857
Stock-based compensation			7,428
Ending balance	676,228		676,228
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			23
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			1,391,256
Net income (loss)			17,372
Dividends on common stock			(4,599)
Ending balance	1,404,029		1,404,029
Accumulated Other Comprehensive Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(21,008)
Ending balance	(21,008)		(21,008)
Trust for Benefit of Employees [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(112,106)
Ending balance	(112,106)		(112,106)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			(446,476)
Treasury Stock, Value, Acquired, Cost Method			(300)
Ending balance	$ (446,776)		$ (446,776)