CONDENSED CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Business acquisitions [Member]	COMMON STOCK [Member]	CAPITAL IN EXCESS OF PAR VALUE [Member]	CAPITAL IN EXCESS OF PAR VALUE [Member] Business acquisitions [Member]	RETAINED EARNINGS [Member]	TREASURY SHARES [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) [Member]	DEFERRED COMPENSATION [Member]
Balance at Sep. 30, 2017	$ 398,808		$ 20,166	$ 487,077		$ 480,347	$ (489,225)	$ (60,481)	$ (39,076)
Balance (in Shares) at Sep. 30, 2017			80,663				33,557
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	30,989					30,989
Dividend	(2,990)					(2,990)
Shares withheld on employee taxes on vested equity awards (in shares)							191
Shares withheld on employee taxes on vested equity awards	(4,332)						$ (4,332)
Amortization of deferred compensation	817								817
Equity awards granted, net (in shares)			895
Equity awards granted, net	0		$ 223	(223)
ESOP allocation of common stock	608			608
Stock-based compensation	2,555			2,555
Other comprehensive income, net of tax	8,358							8,358
Balance at Dec. 31, 2017	434,813		$ 20,389	490,017		508,346	$ (493,557)	(52,123)	(38,259)
Balance (in Shares) at Dec. 31, 2017			81,558				33,748
Balance at Sep. 30, 2017	398,808		$ 20,166	487,077		480,347	$ (489,225)	(60,481)	(39,076)
Balance (in Shares) at Sep. 30, 2017			80,663				33,557
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	127,096
Other comprehensive income, net of tax	19,954
Balance at Jun. 30, 2018	466,087		$ 20,365	499,128		554,922	$ (534,813)	(40,527)	(32,988)
Balance (in Shares) at Jun. 30, 2018			81,460				35,845
Balance at Dec. 31, 2017	434,813		$ 20,389	490,017		508,346	$ (493,557)	(52,123)	(38,259)
Balance (in Shares) at Dec. 31, 2017			81,558				33,748
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	90,280					90,280
Dividend	(46,660)					(46,660)
Shares withheld on employee taxes on vested equity awards (in shares)							6
Shares withheld on employee taxes on vested equity awards	(114)						$ (114)
Amortization of deferred compensation	855								855
Common stock acquired (in shares)							1,438
Common stock acquired	(28,415)						$ (28,415)
Equity awards granted, net (in shares)			(84)
Equity awards granted, net	0		$ (20)	20
ESOP allocation of common stock	493			493
Stock-based compensation	2,365			2,365
Other comprehensive income, net of tax	20,401							20,401
Balance at Mar. 31, 2018	474,018		$ 20,369	492,895		551,966	$ (522,086)	(31,722)	(37,404)
Balance (in Shares) at Mar. 31, 2018			81,474				35,192
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,827					5,827
Dividend	(2,871)					(2,871)
Shares withheld on employee taxes on vested equity awards (in shares)							2
Shares withheld on employee taxes on vested equity awards	(32)						$ (32)
Amortization of deferred compensation	4,416								4,416
Common stock acquired (in shares)							651
Common stock acquired	(12,695)						$ (12,695)
Equity awards granted, net (in shares)			(14)
Equity awards granted, net	0		$ (4)	4
ESOP allocation of common stock	2,805			2,805
Stock-based compensation	2,452	$ 972		2,452	$ 972
Other comprehensive income, net of tax	(8,805)							(8,805)
Balance at Jun. 30, 2018	466,087		$ 20,365	499,128		554,922	$ (534,813)	(40,527)	(32,988)
Balance (in Shares) at Jun. 30, 2018			81,460				35,845
Balance at Sep. 30, 2018	474,391		$ 20,380	503,396		550,523	$ (534,830)	(34,112)	(30,966)
Balance (in Shares) at Sep. 30, 2018			81,520				35,846
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,753					8,753
Dividend	(3,143)					(3,143)
Shares withheld on employee taxes on vested equity awards (in shares)							83
Shares withheld on employee taxes on vested equity awards	(1,058)						$ (1,058)
Amortization of deferred compensation	856								856
Common stock acquired (in shares)							29
Common stock acquired	(290)						$ (290)
Equity awards granted, net (in shares)			1,201
Equity awards granted, net	0		$ 300	(300)
ESOP allocation of common stock	(8)			(8)
Stock-based compensation	2,933	250		2,933	250
Other comprehensive income, net of tax	(5,450)							(5,450)
Balance at Dec. 31, 2018	471,561		$ 20,680	506,271		550,460	$ (536,178)	(39,562)	(30,110)
Balance (in Shares) at Dec. 31, 2018			82,721				35,958
Balance at Sep. 30, 2018	474,391		$ 20,380	503,396		550,523	$ (534,830)	(34,112)	(30,966)
Balance (in Shares) at Sep. 30, 2018			81,520				35,846
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21,192
Other comprehensive income, net of tax	(3,605)
Balance at Jun. 30, 2019	488,165		$ 20,692	514,639		555,780	$ (536,308)	(37,717)	(28,921)
Balance (in Shares) at Jun. 30, 2019			82,769				35,969
Balance at Dec. 31, 2018	471,561		$ 20,680	506,271		550,460	$ (536,178)	(39,562)	(30,110)
Balance (in Shares) at Dec. 31, 2018			82,721				35,958
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(1,156)					(1,156)
Dividend	(3,704)					(3,704)
Shares withheld on employee taxes on vested equity awards (in shares)							3
Shares withheld on employee taxes on vested equity awards	(48)						$ (48)
Amortization of deferred compensation	507								507
Common stock acquired (in shares)							8
Common stock acquired	(82)						$ (82)
Equity awards granted, net (in shares)			48
Equity awards granted, net	0		$ 12	(12)
ESOP allocation of common stock	601			601
Stock-based compensation	3,422	303		3,422	303
Other comprehensive income, net of tax	2,880							2,880
Balance at Mar. 31, 2019	474,284		$ 20,692	510,585		545,600	$ (536,308)	(36,682)	(29,603)
Balance (in Shares) at Mar. 31, 2019			82,769				35,969
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,595					13,595
Dividend	(3,415)					(3,415)
Amortization of deferred compensation	682								682
ESOP allocation of common stock	435			435
Stock-based compensation	3,332	$ 287		3,332	$ 287
Other comprehensive income, net of tax	(1,035)							(1,035)
Balance at Jun. 30, 2019	$ 488,165		$ 20,692	$ 514,639		$ 555,780	$ (536,308)	$ (37,717)	$ (28,921)
Balance (in Shares) at Jun. 30, 2019			82,769				35,969