Common Stock Repurchases (Details) - USD ($) shares in Millions	3 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Mar. 31, 2016
Common Stock Repurchases [Abstract]
Common stock repurchased and retired (in shares)	0.5	0.3
Common stock repurchased and retired	$ 11,700,000	$ 7,800,000
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Authorized amount for share repurchase programs			$ 100,000,000.0
Remaining authorized repurchase amount			$ 202,800,000.0