Annual report pursuant to Section 13 and 15(d)

Debt (Details)

v3.6.0.2
Debt (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities $ 442.4 $ 448.5
Current Maturities of Long-term Debt (5.9) (6.0)
Long-Term Debt, Net 436.5 442.5
Long-term Debt Repurchased 0.0 0.0
Maturities of Long-term Debt [Abstract]    
2017 5.9  
2018 5.7  
2019 5.7  
2020 5.8  
2021 152.4  
Thereafter 266.9  
Total Long-Term Debt Including Current Maturities 442.4 448.5
Line of Credit Facility [Abstract]    
Letters of Credit Outstanding, Amount $ 6.5  
Minimum [Member]    
Line of Credit Facility [Abstract]    
Debt Instrument, Covenant, Interest Coverage Ratio 3.00  
Maximum [Member]    
Line of Credit Facility [Abstract]    
Debt Instrument, Covenant, Leverage Ratio 3.50  
Line of Credit [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Maximum Borrowing Capacity $ 300.0  
Line of Credit Facility, Remaining Borrowing Capacity 295.7  
Line of Credit Facility, Increase (Decrease), Other, Net $ 100.0  
Line of Credit Facility, Commitment Fee Percentage 0.20%  
Line of Credit [Member] | Minimum [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Commitment Fee Percentage 0.125%  
Line of Credit [Member] | Maximum [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Commitment Fee Percentage 0.35%  
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Interest Rate During Period 1.30%  
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Interest Rate During Period 1.00%  
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Interest Rate During Period 1.90%  
Line of Credit [Member] | Base Rate [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Interest Rate During Period 0.30%  
Line of Credit [Member] | Base Rate [Member] | Minimum [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Interest Rate During Period 0.00%  
Line of Credit [Member] | Base Rate [Member] | Maximum [Member]    
Line of Credit Facility [Abstract]    
Line of Credit Facility, Interest Rate During Period 0.90%  
Letter of Credit [Member]    
Line of Credit Facility [Abstract]    
Letters of Credit Outstanding, Amount $ 4.3  
Notes Due 2027 [Member]    
Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities $ 162.3 162.2
Interest Rate 7.125%  
Due date 2027  
Discount on Long-term Debt $ 0.4 0.4
Debt Issuance Costs, Net 0.5 0.6
Maturities of Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities $ 162.3 162.2
Senior Notes Due 2021 [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Redemption Price, Percentage, Triggering Event 101.00%  
Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities [1] $ 147.8 $ 149.6
Interest Rate 4.625% 4.625%
Due date 2021  
Debt Issuance Costs, Net $ 1.9 $ 2.3
Maturities of Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities [1] 147.8 149.6
Debentures Due 2023 [Member]    
Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities [1] $ 103.4 $ 104.7
Interest Rate 7.375% 7.375%
Due date 2023  
Discount on Long-term Debt $ 0.2 $ 0.2
Debt Issuance Costs, Net 0.2 0.3
Maturities of Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities [1] 103.4 104.7
Loan With Fond Du Lac County Economic Development Corporation Due 2021 [Member]    
Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities $ 23.8 28.1
Interest Rate 2.00%  
Due date 2021  
Discount on Long-term Debt $ 3.8 4.5
Debt Issuance Costs, Net 0.1 0.1
Maturities of Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities 23.8 28.1
Line of Credit Facility [Abstract]    
Total Loan Forgiveness $ 2.1 $ 2.0
Annual Forgiveness Percent 43.00% 41.00%
Loan With Fond Du Lac County Economic Development Corporation Due 2021 [Member] | Maximum [Member]    
Line of Credit Facility [Abstract]    
Annual Forgiveness Percent 43.00%  
Notes Payable Through 2027 [Member]    
Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities $ 5.1 $ 3.9
Interest Rate 5.892%  
Due date 2027  
Maturities of Long-term Debt [Abstract]    
Total Long-Term Debt Including Current Maturities $ 5.1 $ 3.9
[1] Included in Senior notes, 4.625% due 2021 and Debentures, 7.375% due 2023 at December 31, 2016 and December 31, 2015, are the aggregate fair values related to the fixed-to-floating interest rate swaps as discussed in Note 14 – Financial Instruments.