Acquisitions and Exit Activities (Schedule of Purchase Price Allocation) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Goodwill	$ 2,286		$ 2,018	$ 2,018
Midstream natural gas gathering assets
Assets
Cash		$ 83
Accounts receivable		24
Inventory		6
Property, plant, and equipment, net		730
Goodwill		268
Customer relationship intangibles		770
Other current assets		1
Total assets		1,882
Liabilities
Accounts payable		19
Other current liabilities		14
Long-term debt		204
Other long-term liabilities		26
Total liabilities		263
Less noncontrolling interest		390
Total cash consideration		$ 1,229