Notes Receivable and Current Expected Credit Losses (Changes in Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 1,741	$ 3,202	$ 2,584	$ 0
Unrealized credit loss provision (release)	388	(117)	333	260
Extinguishment due to acquisition	0	0	(788)	0
Ending balance	2,129	3,085	2,129	3,085
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 0	$ 0	$ 0	$ 2,825