Share-Based Compensation (Expense Related to Non-vested Stock Awards) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Total pre-tax share-based compensation expense	$ 12.1	$ 15.8		$ 12.9
Excess tax benefit (deficiency) on share-based compensation	(1.7)	(0.5)	[1]	(0.7)
Non-Qualified Stock Option Expense [Member]
Total pre-tax share-based compensation expense	1.5	2.3		5.5
Non-Vested Stock Awards Expense [Member]
Total pre-tax share-based compensation expense	0.0	0.0		0.2
Immediately Vested Stock Awards Expense [Member]
Total pre-tax share-based compensation expense	0.0	0.8		0.0
Stock Unit Awards [Member]
Total pre-tax share-based compensation expense	4.5	8.0		5.2
Performance-Based Non-Vested Stock Awards Expense [Member]
Total pre-tax share-based compensation expense	$ 6.1	$ 4.7		$ 2.0

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