Share-Based Compensation (Details 2) $ / shares in Units, shares in Thousands, $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($) $ / shares shares
Restricted Stock Awards and Restricted Stock Units (RSUs) | Minimum
Equity stock-based compensation
Vesting terms	3 years
Restricted Stock Awards and Restricted Stock Units (RSUs) | Maximum
Equity stock-based compensation
Vesting terms	5 years
Restricted Stock
Restricted shares and unit activity
Non-vested at the beginning of the period (in shares) | shares	16
Vested (in shares) | shares	(14)
Non-vested at the end of the period (in shares) | shares	2
Weighted-average fair value per share
Non-vested at the beginning of the period (in dollars per share)	$ 27.94
Vested (in dollars per share)	28.75
Non-vested at the end of the period (in dollars per share)	$ 21.42
Restricted Stock Units (RSUs)
Restricted shares and unit activity
Non-vested at the beginning of the period (in shares) | shares	434
Granted (in shares) | shares	166
Vested (in shares) | shares	(142)
Cancelled (in shares) | shares	(9)
Non-vested at the end of the period (in shares) | shares	449
Weighted-average fair value per share
Non-vested at the beginning of the period (in dollars per share)	$ 59.61
Granted (in dollars per share)	82.23
Vested (in dollars per share)	55.96
Cancelled (in dollars per share)	64.51
Non-vested at the end of the period (in dollars per share)	$ 69.01
Unrecognized compensation cost | $	$ 16
Weighted-average period for amortization of unrecognized compensation cost	2 years