Certain Employee Benefit and Stock Based Compensation Plans (Narrative) (Details) - USD ($) shares in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 88,000,000	$ 104,000,000
Unamortized share-based compensation expense related to nonvested equity compensation arrangements	$ 252,000,000
Period over which unamortized share-based compensation expense will be amortized.	5 years
Treasury stock activity (in shares)	1.1
Nonvested cash-payable incentive/performance units and restricted share units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value	$ 74,000,000
Service based vesting period	3 years
Unamortized compensation expense amortization period	4 years