Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Mar. 31, 2021
Significant Accounting Policies [Line Items]
Total Assets	$ 3,370,888			$ 2,221,552					$ 2,725,913
Total Liabilities	1,881,514								1,291,516
Revision of Prior Period, Reclassification, Adjustment | Commissions and Related Revenue [Member]
Significant Accounting Policies [Line Items]
Revenue from Contract with Customer	375	$ 150	$ 215	$ 185	$ 249	$ 320	$ 25	$ (2)
Variable Interest Entity, Primary Beneficiary [Member]
Significant Accounting Policies [Line Items]
Total Assets	377,878								343,806
Total Liabilities	$ 164,779								$ 114,032