Stock-Based Compensation Plans (Details 2) shares in Millions	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Number of Shares (in millions)
Beginning option balance (shares) | shares	1.4
Options exercised (in shares) | shares	(0.3)
Options forfeited (in shares) | shares	(0.3)
Ending option balance (shares) | shares	0.8
Weighted Average Exercise Price (per share)
Beginning balance (in dollars per share) | $ / shares	$ 44.41
Options exercised (in dollars per share) | $ / shares	35.45
Options forfeited (in dollars per share) | $ / shares	79.99
Ending balance (in dollars per share) | $ / shares	$ 37.37