CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Statement of Stockholders' Equity [Abstract]
Dividend declared per share (USD per share)	$ 0.40	$ 0.40	$ 0.34
Changes in unrealized gains (losses) on marketable securities, tax	$ (58)	$ 83	$ (62)
Changes in unrealized losses on cash flow hedges, tax	0	0	(9)
Actuarial gain or loss arising in the year, tax	$ 161	$ (115)	$ (471)