Derivative Instruments (Detail 3) (Details) - USD ($) $ in Millions		Mar. 31, 2018		Dec. 31, 2017
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative assets, current	[1],[2]	$ 197		$ 174
Derivative Asset, Noncurrent	[1],[2]	228		218
Long-term derivative liabilities	[1],[2]	(178)		(119)
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(310)		14
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		219		62
Derivative Liability, Current	[1],[2]	(338)		(197)
Derivative Liability	[2]	(516)		(316)
Derivative, Collateral, Right to Reclaim Cash		206		155
Derivative, Fair Value, Net	[2]	(91)		76
Derivative Asset	[2]	425		392
Derivative Financial Instruments, Assets [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		1,760		1,367
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(1,335)		(975)
Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative assets, current	[2]	0		0
Derivative Asset, Noncurrent	[2]	0		0
Long-term derivative liabilities	[2]	0		0
Derivative Liability, Current	[2]	0		0
Derivative Liability		(733)		(790)
Derivative Asset		629		746
Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative assets, current	[2]	173		167
Derivative Asset, Noncurrent	[2]	184		199
Long-term derivative liabilities	[2]	(170)		(105)
Derivative Liability, Current	[2]	(325)		(180)
Derivative Liability	[3]	(1,316)		(529)
Derivative Asset	[3]	1,063		592
Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative assets, current	[2]	24		7
Derivative Asset, Noncurrent	[2]	44		19
Long-term derivative liabilities	[2]	(8)		(14)
Derivative Liability, Current	[2]	(13)		(17)
Derivative Liability		(21)		(34)
Derivative Asset		68		29
Fair Value, Inputs, Level 3 [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Margin/Cash (Received) Posted Subject to Master Netting Arrangement		(2)		0
Fair Value, Inputs, Level 3 [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability		0		0
Derivative Asset		0		0
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability	[3]	(132)		(68)
Derivative Asset	[3]	263		265
Fair Value, Inputs, Level 3 [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability		0		0
Derivative Asset		0		0
Derivative Assets, Current [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		1,329	[4]	1,040	[1]
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(1,132)	[4]	(866)	[1]
Derivative Assets, Current [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		489		672
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(489)		(672)
Derivative Assets, Current [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		816		361
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(643)		(194)
Derivative Assets, Current [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		24		7
Derivative Asset, Collateral, Obligation to Return Cash, Offset		0		0
Derivative Assets, Non-current [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		431	[4]	327	[1]
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(203)	[4]	(109)	[1]
Derivative Assets, Non-current [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		140		74
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(140)		(74)
Derivative Assets, Non-current [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		247		231
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(63)		(32)
Derivative Assets, Non-current [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		44		22
Derivative Asset, Collateral, Obligation to Return Cash, Offset		0		(3)
Derivative Liabilities, Current [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		1,613	[4]	1,108	[1]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		1,275	[4]	911	[1]
Derivative Liabilities, Current [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		561		702
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		561		702
Derivative Liabilities, Current [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		1,039		389
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		714		209
Derivative Liabilities, Current [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		13		17
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		0		0
Derivative Liabilities, Non-current [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		457	[4]	245	[1]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		279	[4]	126	[1]
Derivative Liabilities, Non-current [Member] | Future [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		172		88
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		172		88
Derivative Liabilities, Non-current [Member] | Forward Contracts [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		277		140
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		107		35
Derivative Liabilities, Non-current [Member] | Interest Rate Hedging Instruments
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		8		17
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		0		3
Derivative Financial Instruments, Liabilities [Member]
Derivative Instruments Subject to Master Netting Arrangement [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		2,070		1,353
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		$ 1,554		$ 1,037

[1] At December 31, 2017, current and long-term derivative assets are shown net of collateral of $(8) million and $(2) million, respectively, and current and long-term derivative liabilities are shown net of collateral of $52 million and $20 million, respectively.

[2] At March 31, 2018 and December 31, 2017, we had $206 million and $155 million of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements.

[3] Includes OTC swaps and options and retail contracts.

[4] At March 31, 2018, current and long-term derivative assets are shown net of collateral of $(21) million and $(3) million, respectively, and current and long-term derivative liabilities are shown net of collateral of $164 million and $79 million, respectively.