Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 28, 2017	Feb. 29, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 1,723,145
Net income	14,259	$ 13,127
Dividends on common stock	$ (2,215)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)	74,854
Stock Issued During Period, Value, Stock Options Exercised	$ 662
Stock Issued During Period, Value, Share-based Compensation, Gross	0
Stock-based compensation	3,152
Stock repurchases	(2,543)
Ending balance	$ 1,736,460
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding (in shares)	(116,224,000)
Beginning balance	$ 116,224
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)	75,000
Stock Issued During Period, Value, Stock Options Exercised	$ 75
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures (in shares)	0
Stock Issued During Period, Value, Share-based Compensation, Gross	$ 0
Common Stock, Shares, Outstanding (in shares)	(116,299,000)
Ending balance	$ 116,299
Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	696,938
Stock Issued During Period, Value, Stock Options Exercised	587
Stock Issued During Period, Value, Share-based Compensation, Gross	(3,021)
Stock-based compensation	3,152
Ending balance	697,656
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,563,742
Net income	14,259
Dividends on common stock	(2,215)
Ending balance	1,575,786
Accumulated Other Comprehensive Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(16,057)
Ending balance	$ (16,057)
Grantor Stock Ownership Trust
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding (in shares)	(9,432,000)
Beginning balance	$ (102,300)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures (in shares)	279,000
Stock Issued During Period, Value, Share-based Compensation, Gross	$ 3,021
Common Stock, Shares, Outstanding (in shares)	(9,153,000)
Ending balance	$ (99,279)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding (in shares)	(21,720,000)
Beginning balance	$ (535,402)
Stock repurchases	$ (2,543)
Treasury Stock, Shares, Acquired (in shares)	(152,000)
Common Stock, Shares, Outstanding (in shares)	(21,872,000)
Ending balance	$ (537,945)