Stock-Based Compensation

3 Months Ended

Mar. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

STOCK-BASED COMPENSATION

For employee awards, equity classified stock-based compensation cost is measured at the service inception date or the grant date, based on the estimated achievement of certain performance metrics or the fair value of the award, and is recognized as expense or capitalized as a component of property, plant and equipment over the requisite service period.

Pretax stock-based compensation costs, the tax benefit associated with stock-based compensation expense, and stock-based compensation costs capitalized are included in the following table.

	Three Months Ended
	March 31,
(in millions)	2016		2015
Restricted stock unit awards	$	7	$	9
Performance awards	5		5
Pretax stock-based compensation cost	$	12	$	14
Tax benefit associated with stock-based compensation expense	$	4	$	5
Stock-based compensation costs capitalized	1		1