Stock Based Compensation (Stock based compensation expense) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation		$ 4,612		$ 3,014	$ 11,110		$ 9,177
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	[1]	4,612		3,014	10,748		9,177
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation		$ 0	[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.