Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Abstract]
Adjustment of deferred tax balances	$ 6.5
Federal research and development credits	5.2
Reversal of reserves for uncertain tax postions	1.8	12.3	9.9
Settlement of 2010 IRS audit	5.2
Non-deductible transaction costs	3.3
Effect of expiration of statute of limitations during next twelve months	2.4
Impact of charge resulting from enactment of Michigan Corporate Income Tax that eliminated certain future tax deductions			10.8
Reduction of deferred tax balances based on application of enacted state tax statutes			6.8
State tax operating loss carryforward	2,500
Tax effect of change in method of accounting for repairs and maintenance costs			53.9
Gross tax liability for tax positions that may not be sustained under a more likely than not threshold	9.3
Additional interest recognized on tax liability	0.6		2.1
Accrued interest on tax liability	$ 0.6	$ 2.1