Common Stock Repurchases (Details) - USD ($) shares in Millions	3 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Sep. 30, 2017
Common Stock Repurchases [Abstract]
Common stock repurchased and retired (in shares)	1.1	0.6
Common stock repurchased and retired	$ 45,000,000	$ 18,100,000
Authorized amount for share repurchase programs			$ 250,000,000.0
Remaining authorized repurchase amount	$ 175,000,000