Stock Based Compensation (Stock based compensation expense) (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2020		Jun. 30, 2019	Jun. 30, 2020		Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation		$ 3,328		$ 3,248	$ 6,498		$ 6,163
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	[1]	2,966		3,248	6,136		6,163
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation		$ 362	[2]	$ 0	$ 362	[2]	$ 0

[1] Includes service-based and performance-based restricted stock units.

[2] Represents expense related to a modification of vested stock options.