Financial Instruments Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017
Predecessor [Member]
Schedule of Held-to-maturity Securities [Line Items]
Proceeds from Sale of Available-for-sale Securities	$ 788
Cash Equivalents [Member] | Successor [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities		$ 5,205
Cash Equivalents [Member] | Predecessor [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	2,713
Marketable Securities [Member] | Successor [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities		$ 952
Marketable Securities [Member] | Predecessor [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	$ 1,362