Debt - Summary of Carrying Amount and Fair Value of Financial Instruments (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Carrying Amounts and Fair Values of Financial Instruments [Line Items]    
Short-term borrowings $ 2.8 $ 0
fss_LongTermDebtAndCapitalLeaseObligationsCurrentAndNoncurrent 50.1 50.2
Long term debt and capital lease obligations 6.2 6.2
Short-term Debt [Member]    
Carrying Amounts and Fair Values of Financial Instruments [Line Items]    
Short-term borrowings 2.8 0
Short-term Debt, Fair Value 2.8 0
Long-term Debt    
Carrying Amounts and Fair Values of Financial Instruments [Line Items]    
fss_LongTermDebtAndCapitalLeaseObligationsCurrentAndNoncurrent 50.1 [1] 50.2 [1]
Long-term Debt, Fair Value $ 50.1 [1] $ 50.2 [1]
[1] Long-term borrowings includes current portions of long-term debt and current portions of capital lease obligations of $6.2 million and $6.2 million as of March 31, 2015 and December 31, 2014, respectively.