CONDENSED CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	COMMON STOCK	CAPITAL IN EXCESS OF PAR VALUE	RETAINED EARNINGS	TREASURY SHARES	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	DEFERRED COMPENSATION
Balance (in shares) at Sep. 30, 2019		82,775			35,969
Balance at Sep. 30, 2019	$ 477,763	$ 20,694	$ 519,017	$ 568,516	$ (536,308)	$ (65,916)	$ (28,240)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	10,612			10,612
Dividend	(3,392)			(3,392)
Shares withheld on employee taxes on vested equity awards (in shares)					80
Shares withheld on employee taxes on vested equity awards	(1,758)				$ (1,758)
Amortization of deferred compensation	629						629
Equity awards granted, net (in shares)		182
Equity awards granted, net	0	$ 45	(45)
ESOP allocation of common stock	609		609
Stock-based compensation	3,150		3,150
Stock-based consideration	239		239
Other comprehensive income, net of tax	6,841					6,841
Balance (in shares) at Dec. 31, 2019		82,957			36,049
Balance at Dec. 31, 2019	494,693	$ 20,739	522,970	575,736	$ (538,066)	(59,075)	(27,611)
Balance (in shares) at Sep. 30, 2019		82,775			35,969
Balance at Sep. 30, 2019	477,763	$ 20,694	519,017	568,516	$ (536,308)	(65,916)	(28,240)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	33,338
Other comprehensive income, net of tax	709
Balance (in shares) at Jun. 30, 2020		83,735			36,310
Balance at Jun. 30, 2020	508,455	$ 20,934	531,387	591,482	$ (543,787)	(65,207)	(26,354)
Balance (in shares) at Dec. 31, 2019		82,957			36,049
Balance at Dec. 31, 2019	494,693	$ 20,739	522,970	575,736	$ (538,066)	(59,075)	(27,611)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	895			895
Dividend	(3,422)			(3,422)
Shares withheld on employee taxes on vested equity awards (in shares)					261
Shares withheld on employee taxes on vested equity awards	(5,721)				$ (5,721)
Amortization of deferred compensation	629						629
Equity awards granted, net (in shares)		784
Equity awards granted, net	0	$ 196	(196)
ESOP allocation of common stock	435		435
Stock-based compensation	3,662		3,662
Stock-based consideration	117		117
Other comprehensive income, net of tax	(14,834)					(14,834)
Balance (in shares) at Mar. 31, 2020		83,741			36,310
Balance at Mar. 31, 2020	476,454	$ 20,935	526,988	573,209	$ (543,787)	(73,909)	(26,982)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21,831			21,831
Dividend	(3,558)			(3,558)
Amortization of deferred compensation	628						628
Equity awards granted, net (in shares)		(6)
Equity awards granted, net	0	$ (1)	1
ESOP allocation of common stock	352		352
Stock-based compensation	3,930		3,930
Stock-based consideration	116		116
Other comprehensive income, net of tax	8,702					8,702
Balance (in shares) at Jun. 30, 2020		83,735			36,310
Balance at Jun. 30, 2020	508,455	$ 20,934	531,387	591,482	$ (543,787)	(65,207)	(26,354)
Balance (in shares) at Sep. 30, 2020		83,739			27,610
Balance at Sep. 30, 2020	700,151	$ 20,935	583,008	607,518	$ (413,493)	(72,092)	(25,725)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	29,500			29,500
Dividend	(4,469)			(4,469)
Shares withheld on employee taxes on vested equity awards (in shares)					133
Shares withheld on employee taxes on vested equity awards	(2,909)				$ (2,909)
Amortization of deferred compensation	609						609
Equity awards granted, net (in shares)		494
Equity awards granted, net	0	$ 123	(123)
ESOP allocation of common stock	596		596
Stock-based compensation	3,428		3,428
Other comprehensive income, net of tax	13,141					13,141
Balance (in shares) at Dec. 31, 2020		84,233			27,743
Balance at Dec. 31, 2020	740,047	$ 21,058	586,909	632,549	$ (416,402)	(58,951)	(25,116)
Balance (in shares) at Sep. 30, 2020		83,739			27,610
Balance at Sep. 30, 2020	700,151	$ 20,935	583,008	607,518	$ (413,493)	(72,092)	(25,725)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63,319
Other comprehensive income, net of tax	20,655
Balance (in shares) at Jun. 30, 2021		84,420			27,743
Balance at Jun. 30, 2021	785,341	$ 21,104	597,368	658,605	$ (416,402)	(51,437)	(23,897)
Balance (in shares) at Dec. 31, 2020		84,233			27,743
Balance at Dec. 31, 2020	740,047	$ 21,058	586,909	632,549	$ (416,402)	(58,951)	(25,116)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	17,112			17,112
Dividend	(3,217)			(3,217)
Amortization of deferred compensation	609						609
Equity awards granted, net (in shares)		194
Equity awards granted, net	0	$ 48	(48)
ESOP allocation of common stock	756		756
Stock-based compensation	4,349		4,349
Other comprehensive income, net of tax	4,775					4,775
Balance (in shares) at Mar. 31, 2021		84,427			27,743
Balance at Mar. 31, 2021	764,431	$ 21,106	591,966	646,444	$ (416,402)	(54,176)	(24,507)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16,707			16,707
Dividend	(4,546)			(4,546)
Amortization of deferred compensation	610						610
Equity awards granted, net (in shares)		(7)
Equity awards granted, net	0	$ (2)	2
ESOP allocation of common stock	856		856
Stock-based compensation	4,544		4,544
Other comprehensive income, net of tax	2,739					2,739
Balance (in shares) at Jun. 30, 2021		84,420			27,743
Balance at Jun. 30, 2021	$ 785,341	$ 21,104	$ 597,368	$ 658,605	$ (416,402)	$ (51,437)	$ (23,897)