Revenue Recognition (Disaggregation of Revenue by Market Group) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 257,124	$ 219,191
UMG [Member]
Disaggregation of Revenue [Line Items]
Revenue	182,489	173,467	[1]
IMG [Member]
Disaggregation of Revenue [Line Items]
Revenue	48,054	45,769	[1]
EVERFI [Member]
Disaggregation of Revenue [Line Items]
Revenue	26,975	0
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ (394)	$ (45)

[1] Due to the market group change discussed above, we have recast our revenue by market group for the three months ended March 31, 2021 to present them on a consistent basis with the current year.