Shareholders' Equity Stockholders Equity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jan. 01, 2017
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 602		$ 722	$ 736
Cumulative Effect on Retained Earnings, Net of Tax	14
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	20
Other Comprehensive Income (Loss), Net of Tax	15	$ 18
Stock Repurchased and Retired During Period, Value	165
Dividends, Preferred Stock	12
Employee stock compensation expense	14	19
Tax Withholding for Share-based Compensation	(11)
Proceeds from employee stock plans	$ 5	$ 3
Stock Repurchased and Retired During Period, Shares	4.7
Parent [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 599		719	733
Cumulative Effect on Retained Earnings, Net of Tax	14
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	20
Other Comprehensive Income (Loss), Net of Tax	15
Stock Repurchased and Retired During Period, Value	165
Dividends, Preferred Stock	12
Employee stock compensation expense	14
Tax Withholding for Share-based Compensation	(11)
Proceeds from employee stock plans	5
Noncontrolling Interest [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	3		$ 3	$ 3
Cumulative Effect on Retained Earnings, Net of Tax	0
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	0
Other Comprehensive Income (Loss), Net of Tax	0
Stock Repurchased and Retired During Period, Value	0
Dividends, Preferred Stock	0
Employee stock compensation expense	0
Tax Withholding for Share-based Compensation	0
Proceeds from employee stock plans	$ 0