Stock-Based Compensation (Stock Options Activity) (Details) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Stock Option Activity (in shares)
Options Outstanding, Beginning | shares	1,739,972
Granted | shares	57,407
Exercised | shares	(406,588)
Forfeited or expired | shares	(33,958)
Options Outstanding, Ending | shares	1,356,833
Options Exercisable | shares	1,162,235
Weighted Average Exercise Price (in dollars per share)
Options Outstanding, Beginning | $ / shares	$ 28.26
Granted | $ / shares	32.99
Exercised | $ / shares	21.46
Forfeited or expired | $ / shares	45.95
Options Outstanding, Ending | $ / shares	30.05
Options Exercisable | $ / shares	$ 29.28
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options Outstanding, Weighted Average Remaining Contractual Term	6 years 5 months 1 day
Options Exercisable, Weighted Average Remaining Contractual Term	5 years 9 months 18 days
Options Outstanding, Intrinsic Value | $	$ 19.5
Options Exercisable, Intrinsic Value | $	$ 17.4