Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Employee Benefit Plans [Abstract]
Interest cost	$ (32)	$ (32)	$ (64)	$ (64)
Expected return on plan assets	41	52	82	104
Net periodic pension benefit (costs)	$ 9	$ 20	$ 18	$ 40