CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Stockholders' Equity Attributable to Parent	$ (1,459)
Common Stock [Member]
Stockholders' Equity Attributable to Parent	9	$ 7
Preferred Stock [Member]
Stockholders' Equity Attributable to Parent	1,671	3,036
Additional Paid-in Capital [Member]
Stockholders' Equity Attributable to Parent	14,439	12,521
Treasury Stock - Common [Member]
Stockholders' Equity Attributable to Parent	$ (33)	$ (31)
Purchase of shares for company benefit plans, shares	1,185,517	10,100
Release of shares from company benefit plans, shares	38,013	63,318
Preferred Stock, Exchanged for Shares of Common Stock [Member] | Common Stock [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	9,966,000	1,022,000
Preferred Stock, Exchanged for Shares of Common Stock [Member] | Preferred Stock [Member]
Conversion of Stock, Shares Converted	236,048	25,802
Preferred Stock, Exchanged for Shares of Common Stock [Member] | Additional Paid-in Capital [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	9,965,835	1,021,506
Contingent Convertible Senior Notes Exchanged for Shares of Common Stock [Member] | Common Stock [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	0	14,699,000
Contingent Convertible Senior Notes Exchanged for Shares of Common Stock [Member] | Additional Paid-in Capital [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	0	14,699,368
Senior Notes Exchanged for Shares of Common Stock [Member] | Common Stock [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	0	2,556,000
Senior Notes Exchanged for Shares of Common Stock [Member] | Additional Paid-in Capital [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	0	2,555,979