Earnings per Share and Shareholders' Equity Share Repurchase (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020	Nov. 30, 2020	Aug. 31, 2020	Nov. 30, 2019	Aug. 31, 2019
Equity [Abstract]
Stock Repurchased During Period, Value				$ 17,800
Treasury Stock, Shares	22,799,230		22,799,230			22,799,230
Stock Repurchase Program, Authorized Amount	$ 667,700		$ 667,700
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	5,200,770		5,200,770
Stock Repurchased During Period, Shares				839,789
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 381,393	$ 354,365	$ 381,393	$ 354,365	$ 367,946	$ 359,226	$ 353,253	$ 301,179
Net (loss) earnings	3,182	2,162	7,780	4,283
Other Comprehensive (Loss) Income, Net of Tax	9,157	(3,052)	10,786	57,875
Stock Issued During Period, Value, Employee Benefit Plan	81	126	182	257
Stock Issued During Period, Value, Restricted Stock Award, Gross	0	0	0	0
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	2,647	3,093	5,227	9,630
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	(1,706)	(1,425)	(1,981)	(4,063)
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	86	86	173	172
Stock Issued During Period, Value, Stock Options Exercised		122		2,631
Retained earnings	$ 925,451		$ 925,451			$ 917,671
Treasury Stock, Value, Acquired, Cost Method				17,805
Accounting Standards Update [Domain]
Retained earnings		$ 206		$ 206
Common Stock [Member]
Stock Issued During Period, Shares, New Issues	82,879,000	82,540,000	82,879,000	82,540,000	82,625,000	82,594,000	82,248,000	81,919,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 16,576	$ 16,508	$ 16,576	$ 16,508	$ 16,525	$ 16,519	$ 16,450	$ 16,384
Stock Issued During Period, Shares, Employee Benefit Plan	4,000	5,000	10,000	11,000
Stock Issued During Period, Value, Employee Benefit Plan	$ 1	$ 1	$ 2	$ 2
Stock Issued During Period, Shares, Restricted Stock Award, Gross	235,000	259,000	255,000	449,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ 47	$ 52	$ 51	$ 90
Stock Issued To Acquired For And Distributed From Rabbi Trust	15,000	11,000	20,000	16,000
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	$ 3	$ 2	$ 4	$ 3
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture		17,000		145,000
Stock Issued During Period, Value, Stock Options Exercised		$ 3		$ 29
Additional Paid-in Capital [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	197,036	189,716	197,036	189,716	195,979	193,492	187,772	181,213
Stock Issued During Period, Value, Employee Benefit Plan	80	125	180	255
Stock Issued During Period, Value, Restricted Stock Award, Gross	(47)	(52)	(51)	(90)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	2,647	3,093	5,227	9,630
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	(1,706)	(1,425)	(1,981)	(4,063)
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	83	84	169	169
Stock Issued During Period, Value, Stock Options Exercised		119		2,602
Treasury Stock [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(667,732)	(658,017)	(667,732)	(658,017)	(667,732)	(667,732)	(658,017)	(640,212)
Treasury Stock, Value, Acquired, Cost Method				(17,805)
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	925,451	923,622	925,451	923,622	922,269	917,671	921,460	915,466
Net (loss) earnings	3,182	2,162	7,780	4,283
Retained Earnings [Member] | Accounting Standards Update [Domain]
Retained earnings		3,873		3,873
AOCI Attributable to Parent [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(89,938)	(117,464)	(89,938)	(117,464)	(99,095)	(100,724)	(114,412)	(171,672)
Other Comprehensive (Loss) Income, Net of Tax	9,157	(3,052)	10,786	57,875
AOCI Attributable to Parent [Member] | Accounting Standards Update [Domain]
Retained earnings		(3,667)		(3,667)
Stock held in trust [member] [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(2,996)	(2,434)	(2,996)	(2,434)	(2,643)	(2,562)	(3,157)	(3,070)
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	(353)	723	(434)	636
Deferred Compensation, Share-based Payments [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,996	2,434	2,996	2,434	$ 2,643	$ 2,562	$ 3,157	$ 3,070
Stock Value Issued to Acquired For and Distributed From Rabbi Trust	$ 353	$ (723)	$ 434	$ (636)