Stock-Based Compensation and Other Employee Benefit Plans (Schedule of Employee Stock Purchase Plans) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Common shares issued (in shares)	35,732	25,638
Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Cash proceeds (in dollars)	$ 1.2	$ 1.0
Employee Stock Purchase Plans [Member] | Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Weighted average price per share (in dollars per share)	$ 34.48	$ 39.99
Weighted average per share grant date fair value (in dollars per share)	$ 8.76	$ 9.79