CONSOLIDATED STATEMENTS OF COMMON STOCK EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per share (in usd per share)	$ 0.975	$ 0.915	$ 0.855
Dividend Reinvestment Plan waiver discount feature (in shares)	0	688,000	0