Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2016

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

Schedule Of Stock-Based Compensation Expense

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				Six Months Ended
	June 30,				June 30,
(in millions)	2016		2015		2016		2015
Restricted stock unit awards	$	10	$	11	$	17	$	20
Performance awards	5		8		10		13
Pretax stock-based compensation cost	$	15	$	19	$	27	$	33
Tax benefit associated with stock-based compensation expense	$	5	$	7	$	9	$	12
Stock-based compensation costs capitalized	1		1		2		2