Stock-Based Compensation (Changes in Stock Appreciation Rights) (Details) - Stock Appreciation Rights (SARs) [Member] $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $	$ 9.5
Shares (2)
Outstanding awards as of beginning of period (in shares) | shares	0.9
Granted (in shares) | shares	0.1
Exercised (in shares) | shares	(0.2)
Outstanding awards as of end of period (in shares) | shares	0.8
Exercisable at end of period (in shares) | shares	0.5
Weighted-Average Exercise Price per Share
Outstanding awards as of beginning of period (in usd per share) | $ / shares	$ 148.98
Granted (in usd per share) | $ / shares	257.08
Exercised (in usd per share) | $ / shares	100.75
Outstanding as of end of period (in shares) | $ / shares	181.15
Exercisable at end of period, Weighted-Average Exercise Price per Share (in usd per share) | $ / shares	$ 152.28