Recast 2017 and 2016 Financial Information (Details 2) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 1,579	$ 11,225	$ 2,541	$ 2,319
Accounts receivable, net	1,448	1,054
Unbilled receivables, net	5,026	3,465
Inventoried costs, net	654	398
Other Assets, Current	973	445
Assets, Current	9,680	16,587
Property, plant and equipment, net of accumulated depreciation of $5,369 for 2018 and $5,066 for 2017	6,372	4,225
Goodwill	18,672	12,455	12,450
Intangible assets, net	1,372	52
Deferred tax assets	94	447
Other non-current assets	1,463	1,362
Assets	37,653	35,128
Accounts Payable, Current	2,182	1,661
Employee-related Liabilities, Current	1,676	1,382
Customer Advances, Current	1,917	1,761
Other Liabilities, Current	2,499	2,288
Liabilities, Current	8,274	7,092
Long-term Debt and Capital Lease Obligations	13,883	14,399
Liability, Defined Benefit Plan, Noncurrent	5,755	5,511
Other Liabilities, Noncurrent	1,446	994
Liabilities	29,466	27,996
Preferred Stock, Value, Issued	0	0
Common Stock, Value, Issued	171	174
Paid-in capital	0	44
Retained Earnings (Accumulated Deficit)	8,068	6,913
Accumulated Other Comprehensive Income (Loss), Net of Tax	(52)	1
Stockholders' Equity Attributable to Parent	8,187	7,132	5,363
Liabilities and Equity	37,653	35,128
Adjustments for change to Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Period Benefit (Cost) [Member] | Adjustments for Change in Accounting Principle [Domain]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, at Carrying Value		0
Accounts receivable, net		0
Unbilled receivables, net		0
Inventoried costs, net		0
Other Assets, Current		0
Assets, Current		0
Property, plant and equipment, net of accumulated depreciation of $5,369 for 2018 and $5,066 for 2017		0
Goodwill		0
Intangible assets, net		0
Deferred tax assets		0
Other non-current assets		0
Assets		0
Accounts Payable, Current		0
Employee-related Liabilities, Current		0
Customer Advances, Current		0
Other Liabilities, Current		0
Liabilities, Current		0
Long-term Debt and Capital Lease Obligations		0
Liability, Defined Benefit Plan, Noncurrent		0
Other Liabilities, Noncurrent		0
Liabilities		0
Preferred Stock, Value, Issued		0
Common Stock, Value, Issued		0
Paid-in capital		0
Retained Earnings (Accumulated Deficit)	(5,897)	(4,719)
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 5,897	4,719
Stockholders' Equity Attributable to Parent		0	0
Liabilities and Equity		0
Accounting Standards Update 2014-09 [Member] | Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, at Carrying Value		0
Accounts receivable, net		225
Unbilled receivables, net		318
Inventoried costs, net		(382)
Other Assets, Current		77
Assets, Current		238
Property, plant and equipment, net of accumulated depreciation of $5,369 for 2018 and $5,066 for 2017		0
Goodwill		0
Intangible assets, net		0
Deferred tax assets		(28)
Other non-current assets		1
Assets		211
Accounts Payable, Current		0
Employee-related Liabilities, Current		0
Customer Advances, Current		144
Other Liabilities, Current		(17)
Liabilities, Current		127
Long-term Debt and Capital Lease Obligations		0
Liability, Defined Benefit Plan, Noncurrent		0
Other Liabilities, Noncurrent		0
Liabilities		127
Preferred Stock, Value, Issued		0
Common Stock, Value, Issued		0
Paid-in capital		0
Retained Earnings (Accumulated Deficit)		84
Accumulated Other Comprehensive Income (Loss), Net of Tax		0
Stockholders' Equity Attributable to Parent		84	$ 104
Liabilities and Equity		$ 211