Common Stock Repurchases (Details) - USD ($) shares in Millions	3 Months Ended	9 Months Ended
	Aug. 31, 2014	Aug. 31, 2015	Aug. 31, 2014	Sep. 30, 2015
Common Stock Repurchases [Abstract]
Common stock repurchased and retired (in shares)	0.7	1.3	2.3
Common stock repurchased and retired	$ 17,600,000	$ 32,900,000	$ 52,600,000
Equity, Class of Treasury Stock [Line Items]
Authorized amount for share repurchase programs		100,000,000
Remaining authorized repurchase amount		$ 14,500,000
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Authorized amount for share repurchase programs				$ 100,000,000.0
Remaining authorized repurchase amount				$ 114,500,000