Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	1 Months Ended	12 Months Ended
	Aug. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Statement of Stockholders' Equity [Abstract]
Dividends declared (USD per share)	$ 2.00	$ 1.91	$ 1.82	$ 3.7625