Derivative Instruments and Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block]

The Company had no derivative instruments included in its Consolidated Statements of Income in 2015 or 2014. The following tables present the effect of derivative instruments on the Company's Consolidated Statements of Income in 2013.

Derivatives in Cash Flow Hedging Relationships

(In millions)	Amount Recognized in Other Comprehensive Income			Amount Reclassified from Accumulated Other Comprehensive Income (Loss) into Income			Amount Recognized in Income
Natural Gas Financial Futures/Swaps	$	(0.2	)	$	5.2		$	—
Interest Rate Swap	—			(0.2		)	—
Total	$	(0.2	)	$	5.0		$	—

Derivatives Not Designated as Hedging Instruments

(In millions)	Amount Recognized in Income
Natural Gas Physical Purchases/Sales	$	(6.1	)
Natural Gas Financial Futures/Swaps	1.0
Total	$	(5.1	)