Share-Based Compensation (Summary of Stock Option Activity) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Number of Shares
Outstanding - beginning of year, Number of Shares (in shares) | shares	38,000
Granted, Number of Shares (in shares) | shares	0
Exercised, Number of Shares (in shares) | shares	(38,000)
Canceled or expired, Number of Shares (in shares) | shares	0
Outstanding - end of year, Number of Shares (in shares) | shares	0
Options exercisable (in shares) | shares	0
Weighted Average Exercise Price
Outstanding - beginning of year, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 19.30
Granted, Weighted Average Exercise Price (in dollars per share) | $ / shares	0.00
Exercised, Weighted Average Exercise Price (in dollars per share) | $ / shares	19.30
Canceled or Expired, Weighted Average Exercise Price (in dollars per share) | $ / shares	0.00
Outstanding - end of year, Weighted Average Exercise Price (in dollars per share) | $ / shares	0.00
Options Exercisable - end of year, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 0.00
Outstanding - end of year, weighted average remaining contractual term	0 years
Options Exercisable, Weighted Average remaining contractual term	0 years
Outstanding - end of year, Aggregate intrinsic value | $	$ 0.0
Options Exercisable, Aggregate intrinsic value | $	$ 0.0