Assets and Liabilities with Recurring Fair Value Measurements (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[1]	$ 784	$ 168
Derivative Asset	[2]	402	302
Effect of Netting and Allocation of Collateral, Asset	[3],[4]	(1,021)	(1,221)
Margin Deposit Assets	[5]	432	343
Assets, Fair Value Disclosure		1,186	470
Derivative Liability	[2]	288	443
Effect of Netting and Allocation of Collateral, Liability	[3],[4]	(1,135)	(1,268)
Margin deposits posted with us by our counterparties	[5],[6]	127	52
Liabilities, Fair Value Disclosure		288	443
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[1]	784	168
Effect of Netting and Allocation of Collateral, Asset	[3],[4]	(872)	(933)
Assets, Fair Value Disclosure		784	168
Effect of Netting and Allocation of Collateral, Liability	[3],[4]	(984)	(932)
Liabilities, Fair Value Disclosure		0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[1]	0	0
Effect of Netting and Allocation of Collateral, Asset	[3],[4]	(131)	(262)
Assets, Fair Value Disclosure		126	116
Effect of Netting and Allocation of Collateral, Liability	[3],[4]	(133)	(310)
Liabilities, Fair Value Disclosure		183	249
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[1]	0	0
Effect of Netting and Allocation of Collateral, Asset	[3],[4]	(18)	(26)
Assets, Fair Value Disclosure		276	186
Effect of Netting and Allocation of Collateral, Liability	[3],[4]	(18)	(26)
Liabilities, Fair Value Disclosure		105	194
Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[7]	539	550
Derivative Liability	[7]	408	769
Forward Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[7]	0	0
Derivative Liability	[7]	0	0
Forward Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[7]	245	338
Derivative Liability	[7]	285	549
Forward Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	[7]	294	212
Derivative Liability	[7]	123	220
Future [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		872	933
Derivative Liability		984	932
Future [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		872	933
Derivative Liability		984	932
Future [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability		0	0
Future [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability		0	0
Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		12	40
Derivative Liability		31	10
Interest Rate Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability		0	0
Interest Rate Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		12	40
Derivative Liability		31	10
Interest Rate Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability		$ 0	$ 0

[1] As of December 31, 2019 and 2018, we had cash equivalents of $573 million and $23 million included in cash and cash equivalents and $211 million and $145 million included in restricted cash, respectively.

[2] At December 31, 2019 and 2018, we had $191 million and $244 million of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Balance Sheets primarily related to initial margin requirements.

[3] Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $112 million, $2 million and nil, respectively, at December 31, 2019. Cash collateral posted with (received from) counterparties allocated to level 1, level 2 and level 3 derivative instruments totaled $(1) million, $48 million and nil, respectively, at December 31, 2018.

[4] We offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation; therefore, amounts recognized for the right to reclaim, or the obligation to return, cash collateral are presented net with the corresponding derivative instrument fair values. See Note 10 for further discussion of our derivative instruments subject to master netting arrangements.

[5] We offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation; therefore, amounts recognized for the right to reclaim, or the obligation to return, cash collateral are presented net with the corresponding derivative instrument fair values. See Note 10 for further discussion of our derivative instruments subject to master netting arrangements.

[6] At December 31, 2019 and 2018, $3 million and $32 million, respectively, were included in current and long-term derivative assets and liabilities, $93 million and $20 million, respectively, were included in other current liabilities and $31 million and nil, respectively, were included in other long-term liabilities on our Consolidated Balance Sheets.

[7] Includes OTC swaps and options.