Stock-Based Compensation (Stock Option Activity) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Number of Options
Options outstanding beginning of the year (in shares) | shares	105,994
Exercised (in shares) | shares	(53,894)
Options outstanding end of the year (in shares) | shares	52,100
Weighted Average Exercise Price
Options outstanding beginning of the year (in dollars per share) | $ / shares	$ 42.95
Exercised (in dollars per share) | $ / shares	42.62
Options outstanding end of the year (in dollars per share) | $ / shares	$ 43.30
Options outstanding, Aggregate Intrinsic Value | $	$ 4