Derivative Instruments (Details Textual) MMBTU in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017 USD ($) MMBTU	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) MMBTU	Jun. 30, 2016 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Typical hedging period				6 years
Net liability aggregate fair value		$ 10,000,000		$ 10,000,000
Collateral provided to counterparties related to derivatives		$ 7,000,000		$ 7,000,000
Cash flow hedging | Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Nonmonetary notional amount of derivatives | MMBTU	[1]	38		38
Loss on cash flow hedge ineffectiveness		$ 0	$ 0	$ 0	$ 0
Cash flow hedging | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Loss on cash flow hedge ineffectiveness		0	$ 0	0	$ 0
Purchases of products and services | Cash flow hedging | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional amounts of foreign exchange forward contracts		$ 111,000,000		$ 111,000,000

[1] * - millions of British Thermal Units