Derivative Instruments (Details Textual) MMBTU in Millions	6 Months Ended
	Jun. 30, 2015 USD ($) MMBTU	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Typical hedging period	3 years
Net liability aggregate fair value	$ 16,000,000
Collateral provided to counterparties related to derivatives	$ 25,000,000
Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Nonmonetary notional amount of derivatives | MMBTU	20
Loss on cash flow hedge ineffectiveness	$ 0	$ 0
Fair value of contracts not designated as cash flow hedges	4,000,000		$ 5,000,000
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Loss on cash flow hedge ineffectiveness	0	$ 0
Notional amounts of foreign exchange forward contracts	99,000,000
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges | Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) that remained in AOCI from cash flow hedges, net of tax	(16,000,000)		(20,000,000)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) that remained in AOCI from cash flow hedges, net of tax	$ 4,000,000		$ 3,000,000