Significant Accounting Policies (Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets
Accounts receivable	$ 938		$ 927	$ 667
Contract assets			185	192
Other current assets	146		108	98
Equity in and advances to unconsolidated affiliates	850		724	452
Deferred income taxes	236		222	294
Other assets	143		147	125
Liabilities
Contract liabilities	484		463	377
Deferred income taxes	16		27
Deferred income from unconsolidated affiliates			0	0
Other liabilities	124	$ 110	202	172
Equity
Retained earnings	1,441	1,256	1,235	998
Accumulated other comprehensive loss	$ (987)		(910)		$ (922)
Calculated under Revenue Guidance in Effect before Topic 606
Assets
Accounts receivable			594		510
Contract assets			496		383
Other current assets			103		93
Equity in and advances to unconsolidated affiliates			716		365
Deferred income taxes			229		300
Other assets			143		124
Liabilities
Contract liabilities			479		368
Deferred income taxes			28
Deferred income from unconsolidated affiliates			95		101
Other liabilities			202		171
Equity
Retained earnings			1,080		$ 854
Accumulated other comprehensive loss			(899)
Adjustments Due to Topic 606
Assets
Equity in and advances to unconsolidated affiliates				87
Adjustments Due to Topic 606 | Difference between Revenue Guidance in Effect before and after Topic 606
Assets
Accounts receivable			333	157
Contract assets			(311)	(191)
Other current assets			5	5
Equity in and advances to unconsolidated affiliates			8	87
Deferred income taxes			(7)	(6)
Other assets			4	1
Liabilities
Contract liabilities			(16)	9
Deferred income taxes			(1)
Deferred income from unconsolidated affiliates			(95)	(101)
Other liabilities			0	1
Equity
Retained earnings			155	$ 144
Accumulated other comprehensive loss			(11)
Equity Method Investments
Assets
Equity in and advances to unconsolidated affiliates		753	724
Equity
Retained earnings		1,264	$ 1,235
Equity Method Investments | Adjustments Due to Topic 606
Assets
Equity in and advances to unconsolidated affiliates		29
Equity
Retained earnings		$ 29