Retirement Plans and Postretirement Benefit Plans Postretirement Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Level 3 Asset Value, Beginning of Period	$ 53.3
Unrealized Gains	(0.5)
Interest Income	1.1
Dividend Income	0.6
Realized Gains	0.4
Administrative Expenses and Charges	(0.1)
Claims Paid	(1.7)
Level 3 Asset Value, End of Period	53.1
Defined Benefit Plan, Fair Value of Plan Assets	61.4		59.6
Postretirement Plan, Expected Future Benefit Payments, Next Twelve Months	15.5
Postretirement Plan, Expected Future Benefit Payments, Year Two	16.1
Postretirement Plan, Expected Future Benefit Payments, Year Three	16.7
Postretirement Plan, Expected Future Benefit Payments in Year Four	17.2
Postretirement Plan, Expected Future Benefit Payments, Year Five	17.7
Postretirement Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	90.7
Postemployment Benefits Liability	1.6		2.6
Group Retiree Medical Insurance Contract [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	53.1	[1]	53.3	[1]
U.S. Equity Mutual Funds Investment [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	7.9		6.0
Money Market Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	0.4		0.3
Fair Value, Inputs, Level 1 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	8.3		6.3
Fair Value, Inputs, Level 1 [Member] | Group Retiree Medical Insurance Contract [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	0	[1]	0	[1]
Fair Value, Inputs, Level 1 [Member] | U.S. Equity Mutual Funds Investment [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	7.9		6.0
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	0.4		0.3
Fair Value, Inputs, Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	53.1		53.3
Fair Value, Inputs, Level 3 [Member] | Group Retiree Medical Insurance Contract [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	53.1	[1]	53.3	[1]
Fair Value, Inputs, Level 3 [Member] | U.S. Equity Mutual Funds Investment [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	$ 0		$ 0

[1] This category represents a group retiree medical insurance contract which invests in a pool of common stocks, bonds and money market accounts, of which a significant portion is comprised of mortgage-backed securities.