CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) $ in Millions	12 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Cash dividends paid per share | $ / shares	$ 1.82
Purchases of common stock	2,100,000
Aggregate cost for purchase of common stock | $	$ 88.6
Common Stock [Member]
Purchases of common stock	2,100,000
KapStone [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	1,600,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable | $	$ 70.1