Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Benefit plans, Net defined pension and other postretirement adjustment arising during the period	$ 44	$ 0
Benefit plans, Prior service credit arising during the period	235	0
Benefit plans, Actuarial loss arising during the period	$ (191)	$ 0
Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Weighted average assumptions, Discount rate, Percent	3.64%
Fair value of plan assets at September 30, 2016	$ 2,600
Benefit plans, Net defined pension and other postretirement adjustment arising during the period	41
Benefit plans, Prior service credit arising during the period	201
Benefit plans, Actuarial loss arising during the period	$ 160
Non-Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Weighted average assumptions, Discount rate, Percent	3.64%
Benefit plans, Net defined pension and other postretirement adjustment arising during the period	$ 3
Benefit plans, Prior service credit arising during the period	34
Benefit plans, Actuarial loss arising during the period	$ 31