Incentive Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2017

Incentive Based Compensation Plans [Abstract]

Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value

The weighted average grant date fair value of these awards was based on the following weighted average Black-Scholes assumptions:

	2017		2016		2015
Exercise price per share	$15.80		$7.22		$29.06
Expected annual dividend yield	1.3	%	2.8	%	2.9	%
Expected life in years	6.4		6.3		6.2
Expected volatility	42	%	36	%	32	%
Risk-free interest rate	2.1	%	1.4	%	1.7	%
Weighted average grant date fair value of stock option awards granted	$6.07		$1.97		$6.84

Schedule of Share-based Compensation, Stock Options, Activity

The following is a summary of stock option award activity in 2017.

	Number	Weighted Average	Weighted Average Remaining	Aggregate Intrinsic Value
	of Shares	Exercise Price	Contractual Term	(in millions)
Outstanding at beginning of year	11,915,533	$27.71
Granted	799,591	$15.80
Exercised	(8,666)	$7.22
Canceled	(2,375,682)	$33.31
Outstanding at end of year	10,330,776	$25.52	4 years	$	13
Exercisable at end of year	8,661,893	$27.91	3 years	$	5
Expected to vest	1,650,737	$13.08	9 years	$	8

Schedule of Nonvested Restricted Stock Units Activity

The following is a summary of restricted stock and restricted stock unit award activity in 2017.

	Awards		Weighted Average Grant Date Fair Value
Unvested at beginning of year	6,933,533		$14.44
Granted	4,198,624		$16.13
Vested & Exercised	(2,472,367	)	$17.67
Canceled	(1,086,945	)	$15.03
Unvested at end of year	7,572,845		$14.24

Schedule of Performance Units, Valuation [Table Text Block]

The key assumptions used in the Monte Carlo simulation to determine the fair value of stock-based performance units granted in 2017, 2016 and 2015 were:

	2017		2016		2015 (a)
Valuation date stock price	$16.93		$16.93		$16.93
Expected annual dividend yield	1.2	%	1.2	%	1.2	%
Expected volatility	54	%	34	%	33	%
Risk-free interest rate	1.9	%	1.7	%	1.4	%
Fair value of stock-based performance units outstanding	$21.63		$19.86		$0.00

^(a) As of December 31, 2017, there were no 2015 performance unit awards outstanding.