Earnings (Loss) per Share Level 4 (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Income (Loss) Attributable to Parent [Abstract]
Income (Loss) from Continuing Operations Attributable to Parent									$ 1,673	$ 1,349	$ 1,225
Preferred Stock Dividends, Income Statement Impact									0	0	10
Income loss from Continuing Operations Net of Tax Available to Common Shareholders									1,673	1,349	1,215
Dilutive Securities, Effect on Basic Earnings Per Share									0	0	10
Income (Loss) from Continuing Operations Net of Tax Available to Common Stockholders Diluted									1,673	1,349	1,225
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 0	$ 9	$ 0	$ 0	$ 37	$ 0	$ (617)	$ 29	9	(551)	(1,049)
Net Income (Loss) Attributable to Parent									1,682	798	176
Net Income (Loss) Available to Common Stockholders, Basic									1,682	798	166
Net Income (Loss) Available to Common Stockholders, Diluted									$ 1,682	$ 798	$ 176
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted Average Number of Shares Outstanding, Basic	406.9	413.8	418.7	422.6	429.6	437.2	450.6	449.8	415.5	441.8	447.7
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements									5.0	6.3	32.2
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants									4.7	12.1	4.5
Weighted Average Number of Shares Outstanding, Diluted	415.9	423.0	428.1	433.7	442.6	450.8	467.9	478.6	425.2	460.2	490.6	[1]
Earnings Per Share, Basic and Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share									$ 4.03	$ 3.05	$ 2.71
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share									0.02	(1.24)	(2.34)
Earnings Per Share, Basic	$ 1.03	$ 0.92	$ 0.99	$ 1.11	$ 0.89	$ 0.89	$ (1.04)	$ 1.10	4.05	1.81	0.37
Income (Loss) from Continuing Operations, Per Diluted Share									3.93	2.93	2.50
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share									0.03	(1.20)	(2.14)
Earnings Per Share, Diluted	$ 1.01	$ 0.90	$ 0.96	$ 1.08	$ 0.86	$ 0.86	$ (1.00)	$ 1.03	$ 3.96	$ 1.73	$ 0.36
Weighted Average Number Diluted Shares Outstanding Assuming Conversion of Preferred Shares									0.0	0.0	6.2

[1] [1]For additional information, see Note 13 - Equity and Note 17 - Stock Compensation Plans of Notes to Consolidated Financial Statements.