Derivative Instruments (Detail 5) (Details) - USD ($) $ in Millions		Dec. 31, 2018		Dec. 31, 2017
Derivative [Line Items]
Derivative, Collateral, Right to Reclaim Cash		$ 244		$ 155
Net derivative assets (liabilities)	[1]	(141)		76
Derivative Asset, Current	[1]	142	[2]	174	[3]
Derivative Asset, Noncurrent	[1]	160	[2]	218	[3]
Derivative Asset	[1]	302		392
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(188)		(14)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		47		62
Derivative Liability, Current	[1]	(303)	[2]	(197)	[3]
Derivative Liability, Noncurrent	[1]	(140)	[2]	(119)	[3]
Derivative Liability	[1]	(443)		(316)
Future [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	0		0
Derivative Asset, Noncurrent	[1]	0		0
Derivative Asset		933		746
Derivative Liability, Current	[1]	0		0
Derivative Liability, Noncurrent	[1]	0		0
Derivative Liability		(932)		(790)
Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	30		7
Derivative Asset, Noncurrent	[1]	10		19
Derivative Asset		40		29
Derivative Liability, Current	[1]	(4)		(17)
Derivative Liability, Noncurrent	[1]	(6)		(14)
Derivative Liability		(10)		(34)
Forward Contracts [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	112		167
Derivative Asset, Noncurrent	[1]	150		199
Derivative Asset	[4]	550		592
Derivative Liability, Current	[1]	(299)		(180)
Derivative Liability, Noncurrent	[1]	(134)		(105)
Derivative Liability	[4]	(769)		(529)
Derivative Assets, Current [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		1,191	[2]	1,040	[3]
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(1,049)	[2]	(866)	[3]
Derivative Assets, Current [Member] | Future [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		820		672
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(820)		(672)
Derivative Assets, Current [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		30		7
Derivative Asset, Collateral, Obligation to Return Cash, Offset		0		0
Derivative Assets, Current [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		341		361
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(229)		(194)
Derivative Assets, Non-current [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		332	[2]	327	[3]
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(172)	[2]	(109)	[3]
Derivative Assets, Non-current [Member] | Future [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		113		74
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(113)		(74)
Derivative Assets, Non-current [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		10		22
Derivative Asset, Collateral, Obligation to Return Cash, Offset		0		(3)
Derivative Assets, Non-current [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		209		231
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(59)		(32)
Derivative Liabilities, Current [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(1,344)	[2]	(1,108)	[3]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		1,041	[2]	911	[3]
Derivative Liabilities, Current [Member] | Future [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(764)		(702)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		764		702
Derivative Liabilities, Current [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(4)		(17)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		0		0
Derivative Liabilities, Current [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(576)		(389)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		277		209
Derivative Liabilities, Non-current [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(367)	[2]	(245)	[3]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		227	[2]	126	[3]
Derivative Liabilities, Non-current [Member] | Future [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(168)		(88)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		168		88
Derivative Liabilities, Non-current [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(6)		(17)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		0		3
Derivative Liabilities, Non-current [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(193)		(140)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		59		35
Derivative Financial Instruments, Assets [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		1,523		1,367
Derivative Asset, Collateral, Obligation to Return Cash, Offset		(1,221)		(975)
Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		(1,711)		(1,353)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		$ 1,268		$ 1,037

[1] At December 31, 2018 and 2017, we had $244 million and $155 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.

[2] At December 31, 2018, current and long-term derivative assets are shown net of collateral of $(58) million and $(8) million, respectively, and current and long-term derivative liabilities are shown net of collateral of $49 million and $64 million, respectively.

[3] 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.

[4] Includes OTC swaps and options.