Stock Based Compensation Stock Based Compensation (Summary of performance-based restricted stock units) (Details) - Performance-based restricted stock units [Member] - $ / shares shares in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Performance-Based Restricted Stock Units, Number of shares outstanding (in shares):
Beginning balance (in shares)		453	206	0
Granted (in shares)	[1]	474	255	206
Vested (in shares)		0	0	0
Forfeited (in shares)		(302)	(8)	0
Ending balance (in shares)		625	453	206
Performance-Based Restricted Stock Units, Weighted average grant date fair value (in dollars per share):
Beginning balance (in dollars per share)		$ 19.37	$ 16.35	$ 0.00
Granted (in dollars per share)	[1]	19.64	21.94	16.35
Vested (in dollars per share)		0.00	0.00	0.00
Forfeited (in dollars per share)		17.76	22.90	0.00
Ending balance (in dollars per share)		$ 20.36	$ 19.37	$ 16.35

[1] Represents the maximum number of performance-based restricted stock units which could be earned.