Revenue Recognition Revenue Recognition - Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts Receivable		$ 47	$ 51	$ 41	$ 48
Provision for doubtful accounts		21	8	11
Allowance for Loan and Lease Losses Write-offs, Net		(25)	(18)	(18)
Allowance for Credit Loss [Member]
Contract with Customer, Asset, Accumulated Allowance for Credit Loss		43	44	21	35
Provision for doubtful accounts		17	9	11
Allowance for Loan and Lease Losses Write-offs, Net		(18)	14	(25)
Trade Accounts Receivable [Member]
Allowance for Doubtful Accounts Receivable		4	7	20	$ 13
Provision for doubtful accounts		4	(1)	0
Allowance for Loan and Lease Losses Write-offs, Net		$ (7)	(32)	$ 7
OpCo [Member]
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease)	[1]		20
OpCo [Member] | Allowance for Credit Loss [Member]
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease)	[1]		0
OpCo [Member] | Trade Accounts Receivable [Member]
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease)	[1]		$ 20

[1] (1) See Note 4 for further details relating to the acquisition of OpCo