Retirement and Employee Benefit Plans (Amounts Recognized in Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss) gain arising during the year	$ (2)	$ (11)
Amortization of net loss	2	2
Curtailments	5
Tax effect	(1)	3
Total	4	(6)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss) gain arising during the year		(2)
Curtailments	3
Tax effect	(1)	1
Total	$ 2	$ (1)