Share-Based Compensation Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accounting corrections	$ 3.4
Pretax [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accounting corrections	$ 4.2
Performance Shares PSU [Member]
Nonvested share activity [Rollforward]
Beginning balance - shares		199,300
Stock units granted - shares	186,800
Cancelled awards - shares	(2,700)
Ending balance - shares	383,400	199,300
Market Share Units MSU [Member]
Nonvested share activity [Rollforward]
Beginning balance - shares		96,200
Stock units granted - shares	82,900
Cancelled awards - shares	0
Ending balance - shares	179,100	96,200
Restricted Stock Units RSU [Member]
Nonvested share activity [Rollforward]
Beginning balance - shares		396,400
Stock units granted - shares	128,700
Cancelled awards - shares	(5,600)
Vested - shares	(65,300)
Ending balance - shares	454,200	396,400
Deferred Stock Units DSU [Member]
Nonvested share activity [Rollforward]
Beginning balance - shares		19,200
Stock units granted - shares	28,300
Cancelled awards - shares	0
Vested - shares	(19,200)
Ending balance - shares	28,300	19,200
PSU MSU Total [Member]
Nonvested share activity [Rollforward]
Beginning balance - shares		295,500
Stock units granted - shares	269,700
Cancelled awards - shares	(2,700)
Ending balance - shares	562,500	295,500
RSU DSU Total [Member]
Nonvested share activity [Rollforward]
Beginning balance - shares		415,600
Stock units granted - shares	157,000
Cancelled awards - shares	(5,600)
Vested - shares	(84,500)
Ending balance - shares	482,500	415,600