Earnings per Share and Shareholders' Equity Share Repurchase (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		126 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Nov. 30, 2021	Aug. 31, 2021	Nov. 30, 2020	Aug. 31, 2020
Equity [Abstract]
Treasury Stock, Shares	22,799,230		22,799,230		22,799,230		22,799,230
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	5,200,770		5,200,770		5,200,770
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 413,023	$ 381,393	$ 413,023	$ 381,393	$ 413,023	$ 409,806	$ 412,198	$ 367,946	$ 359,226
Net (loss) earnings	1,221	3,182	4,009	7,780
Other Comprehensive (Loss) Income, Net of Tax	1,744	9,157	(8,300)	10,786
Stock Issued During Period, Value, Employee Benefit Plan	65	81	150	182
Stock Issued During Period, Value, Restricted Stock Award, Gross	0	0	0	0
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	2,142	2,647	8,289	5,227
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	(1,980)	(1,706)	(3,373)	(1,981)
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	25	$ 86	50	$ 173
Retained earnings	957,348		957,348		957,348		953,339
Treasury Stock, Value	$ 667,732		$ 667,732		667,732		$ 667,732
Treasury Stock, Value, Acquired, Cost Method					$ 667,700
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	5,200,770		5,200,770		5,200,770
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	10,000,000		10,000,000		10,000,000
Common Stock [Member]
Stock Issued During Period, Shares, New Issues	83,345,000	82,879,000	83,345,000	82,879,000	83,345,000	83,092,000	83,022,000	82,625,000	82,594,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 16,669	$ 16,576	$ 16,669	$ 16,576	$ 16,669	$ 16,622	$ 16,604	$ 16,525	$ 16,519
Stock Issued During Period, Shares, Employee Benefit Plan	5,000	4,000	7,000	10,000
Stock Issued During Period, Value, Employee Benefit Plan	$ 1	$ 1	$ 2	$ 2
Stock Issued During Period, Shares, Restricted Stock Award, Gross	247,000	235,000	314,000	255,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 46	$ 47	$ 63	$ 51
Stock Issued To Acquired For And Distributed From Rabbi Trust	1,000	15,000	2,000	20,000
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	$ 0	$ 3		$ 4
Additional Paid-in Capital [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	208,022	197,036	$ 208,022	197,036	208,022	207,817	202,971	195,979	193,492
Stock Issued During Period, Value, Employee Benefit Plan	64	80	148	180
Stock Issued During Period, Value, Restricted Stock Award, Gross	(46)	(47)	(63)	(51)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	2,142	2,647	8,289	5,227
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	(1,980)	(1,706)	(3,373)	(1,981)
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	25	83	50	169
Treasury Stock [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(667,732)	(667,732)	(667,732)	(667,732)	(667,732)	(667,732)	(667,732)	(667,732)	(667,732)
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	957,348	925,451	957,348	925,451	957,348	956,127	953,339	922,269	917,671
Net (loss) earnings	1,221	3,182	4,009	7,780
AOCI Attributable to Parent [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(101,284)	(89,938)	(101,284)	(89,938)	(101,284)	(103,028)	(92,984)	(99,095)	(100,724)
Other Comprehensive (Loss) Income, Net of Tax	1,744	9,157	(8,300)	10,786
Stock held in trust [member] [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(3,089)	(2,996)	(3,089)	(2,996)	(3,089)	(3,092)	(3,067)	(2,643)	(2,562)
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	3	(353)	(22)	(434)
Deferred Compensation, Share-based Payments [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	3,089	2,996	3,089	2,996	$ 3,089	$ 3,092	$ 3,067	$ 2,643	$ 2,562
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	$ (3)	$ 353	$ 22	$ 434