Common Stock (Schedule of Stock Option Activity) (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Shares
Outstanding at beginning of period (in shares) | shares	549
Granted (in shares) | shares	0
Exercised (shares) | shares	(85)
Canceled (in shares) | shares	(1)
Outstanding at end of period (in shares) | shares	463
Exercisable (in shares) | shares	433
Weighted-Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 26.80
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	23.26
Canceled (in dollars per share) | $ / shares	19.67
Outstanding at end of period (in dollars per share) | $ / shares	27.47
Exercisable (in dollars per share) | $ / shares	$ 25.38