CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Accumulated Other Comprehensive Income	Retained Earnings	Noncontrolling Interest
Balance at Sep. 30, 2013	$ 529,775	$ 415,271	$ 7,987	$ 106,250	$ 267
Balance (in shares) at Sep. 30, 2013		68,525
Increase (Decrease) in Shareholders' Equity
Net income	145,396			145,440	(44)
Foreign currency translation	(7,757)		(7,757)
Interest rate hedge, net of income taxes	0
Cash dividends	(12,187)			(12,187)
Dividends on RSUs		$ 493		(493)
Repurchases of common stock	$ (113,135)			(113,135)
Repurchases of common stock (in shares)	(2,700)	(2,672)
Stock compensation expense	$ 17,278	$ 17,278
Stock compensation tax benefit	9,665	9,665
Tax withholding related to RSU vesting	(14,212)	(14,212)
Stock options exercised and RSUs vesting	1,362	$ 1,362
Stock options exercised and RSUs vesting (in shares)		760
Balance at Sep. 30, 2014	556,185	$ 429,857	230	125,875	223
Balance (in shares) at Sep. 30, 2014		66,613
Increase (Decrease) in Shareholders' Equity
Net income	160,049			157,772	2,277
Foreign currency translation	(22,570)		(22,570)
Interest rate hedge, net of income taxes	(25)		(25)
Cash dividends	(11,927)			(11,852)	(75)
Dividends on RSUs		$ 397		(397)
Repurchases of common stock	$ (82,787)			(82,787)
Repurchases of common stock (in shares)	(1,600)	(1,619)
Stock compensation expense	$ 17,237	$ 17,237
Stock compensation tax benefit	9,474	9,474
Tax withholding related to RSU vesting	(11,701)	(11,701)
Stock options exercised and RSUs vesting	868	$ 868
Stock options exercised and RSUs vesting (in shares)		443
Addition of noncontrolling interest from acquisition	896				896
Balance at Sep. 30, 2015	$ 615,699	$ 446,132	(22,365)	188,611	3,321
Balance (in shares) at Sep. 30, 2015	65,437	65,437
Increase (Decrease) in Shareholders' Equity
Net income	$ 180,160			178,362	1,798
Foreign currency translation	(13,828)		(13,828)
Interest rate hedge, net of income taxes	24		24
Cash dividends	(12,761)			(11,701)	(1,060)
Dividends on RSUs		$ 363		(363)
Repurchases of common stock	$ (31,338)			(31,338)
Repurchases of common stock (in shares)	(600)	(587)
Stock compensation expense	$ 18,751	$ 18,751
Stock compensation tax benefit	5,172	5,172
Tax withholding related to RSU vesting	(9,285)	(9,285)
Stock options exercised and RSUs vesting	546	$ 546
Stock options exercised and RSUs vesting (in shares)		373
Balance at Sep. 30, 2016	$ 753,140	$ 461,679	$ (36,169)	$ 323,571	$ 4,059
Balance (in shares) at Sep. 30, 2016	65,223	65,223