Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Allowances for accounts receivable, current	$ 98	$ 131
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Preferred Stock, Dividend Rate, Percentage	11.125%	11.125%
Preferred Stock, Shares Issued	19,250,000	19,250,000
Common stock, par value (in dollars per share)	$ 0.25	$ 0.25
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares outstanding (in shares)	1,178,203,000	1,172,553,000
Common stock, shares issued (in shares)	1,192,986,000	1,192,986,000
Series A Preferred Stock [Member]
Preferred Stock, Shares Outstanding	19,250,000	19,250,000