CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital In Excess Of Par Value [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Deferred Compensation [Member]	Series of Individually Immaterial Business Acquisitions [Member]	Series of Individually Immaterial Business Acquisitions [Member] Capital In Excess Of Par Value [Member]
Balance (in Shares) at Sep. 30, 2016		79,966,000			34,797,000
Balance at Sep. 30, 2016	$ 410,947	$ 19,992	$ 529,980	$ 475,760	$ (501,866)	$ (81,241)	$ (31,678)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	14,912			14,912
Dividends	(10,325)			(10,325)
Tax effect from exercise/vesting of equity awards, net	(13,738)		(97)		$ (13,641)
Tax effect from exercise/vesting of equity awards, net (in shares)					586,000
Amortization of deferred compensation	3,510						3,510
Common stock issued (in Shares)		3,000
Common stock issued	22		22
Common stock acquired (in Shares)					129,000
Common stock acquired	(2,201)				$ (2,201)
Equity awards granted, net (in Shares)		694,000
Equity awards granted, net		$ 174	(174)
Premium on settlement of convertible debt	(73,855)		(73,855)
Issuance of treasury stock in settlement of convertible debt	48,858		20,375		$ 28,483
Issuance of treasury stock in settlement of convertible debt (in shares)					(1,955,000)
ESOP purchase of common stock	(10,908)						(10,908)
ESOP allocation of common stock	2,736		2,736
Stock-based compensation	8,090		8,090
Other comprehensive income (loss), net of taxes	20,760					20,760
Balance (in Shares) at Sep. 30, 2017		80,663,000			33,557,000
Balance at Sep. 30, 2017	398,808	$ 20,166	487,077	480,347	$ (489,225)	(60,481)	(39,076)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	125,678			125,678
Dividends	(55,502)			(55,502)
Shares withheld on employee taxes on vested equity awards (in shares)					200,000
Shares withheld on employee taxes on vested equity awards	(4,495)				$ (4,495)
Amortization of deferred compensation	8,110						8,110
Common stock acquired (in Shares)					2,089,000
Common stock acquired	(41,110)				$ (41,110)
Equity awards granted, net (in Shares)		857,000
Equity awards granted, net		$ 214	(214)
ESOP allocation of common stock	4,756		4,756
Stock-based compensation	10,078		10,078					$ 1,699	$ 1,699
Other comprehensive income (loss), net of taxes	26,369					26,369
Balance (in Shares) at Sep. 30, 2018		81,520,000			35,846,000
Balance at Sep. 30, 2018	474,391	$ 20,380	503,396	550,523	$ (534,830)	(34,112)	(30,966)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	37,287
Dividends	$ (13,676)			(13,676)
Tax effect from exercise/vesting of equity awards, net (in shares)	37,500
Shares withheld on employee taxes on vested equity awards (in shares)	85,847				86,000
Shares withheld on employee taxes on vested equity awards	$ (1,106)				$ (1,106)
Amortization of deferred compensation	2,726						2,726
Common stock acquired (in Shares)					37,000
Common stock acquired	(372)				$ (372)
Equity awards granted, net (in Shares)		1,255,000
Equity awards granted, net		$ 314	(314)
ESOP allocation of common stock	1,512		1,512
Stock-based compensation	13,285		13,285					$ 1,138	$ 1,138
Other comprehensive income (loss), net of taxes	(31,804)					(31,804)
Balance (in Shares) at Sep. 30, 2019		82,775,000			35,969,000
Balance at Sep. 30, 2019	$ 477,763	$ 20,694	$ 519,017	$ 568,516	$ (536,308)	$ (65,916)	$ (28,240)