Fair Value Measurement - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	May. 31, 2014 swap	Mar. 31, 2014 swap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative, Notional Amount	$ 100.0		$ 100.0
Derivative Asset	2.1	$ 0.1	2.1	$ 0.1	$ 0.3
Derivative Liability	0.7	0.5	0.7	0.5	$ 1.7
Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative, (Gain) Loss on Derivative, Net	(1.2)	0.6	(2.5)	(0.3)
Commodity Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative, (Gain) Loss on Derivative, Net	$ 0.4	$ 0.6	$ 0.4	$ 0.7
Institutional Group Two [Member] | Notes Payable to Banks [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.11%		6.11%
Institutional Group Two [Member] | Notes Payable to Banks [Member] | London Interbank Offered Rate (LIBOR) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative, Variable Interest Rate	4.15%		4.15%
Fair Value, Inputs, Level 2 [Member] | Commodity Contract, Diesel [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative, Number of Instruments Held | swap							2
Derivative, Percent of Forecasted Purchases of Commodities							25.00%
Fair Value, Inputs, Level 2 [Member] | Commodity Contract, Natural Gas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative, Number of Instruments Held | swap						2
Derivative, Percent of Forecasted Purchases of Commodities						25.00%