Stock-Based Compensation (Changes in Stock Appreciation Rights) (Details) - Stock Appreciation Rights [Member] shares in Millions	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Shares
Outstanding awards as of beginning of period (in shares) | shares	1.5
Granted (in shares) | shares	0.2
Exercised (in shares) | shares	(0.4)
Forfeited (in shares) | shares	0.0
Outstanding awards as of end of period (in shares) | shares	1.3
Exercisable at end of period (in shares) | shares	0.9
Weighted-Average Exercise Price per Share
Outstanding awards as of beginning of period (in usd per share) | $ / shares	$ 56.20
Granted (in usd per share) | $ / shares	131.87
Exercised (in usd per share) | $ / shares	40.09
Forfeited (in usd per share) | $ / shares	0.00
Outstanding as of end of period (in shares) | $ / shares	72.54
Exercisable at end of period, Weighted-Average Exercise Price per Share (in usd per share) | $ / shares	$ 53.91