Business Combinations - Changes in Contingent Purchase Price Consideration (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Business Combinations [Abstract]
Net Expense (Income)	$ 93	$ 530	$ 753	$ (154)
Cash Settlement Paid	$ 6,122	$ 3,485	$ 7,584	$ 5,886
Shares Issued (number)	16,000	44,000	53,000	81,000