Commitments and Contingencies - Allowance for Credit Losses for Unfunded Loan Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 4,467	$ 3,112
(Recovery) provision for credit losses	(164)	1,616
Balance at end of period	4,303	6,077	$ 3,112
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member
Impact of new accounting standard
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	0	1,349
Balance at end of period			$ 1,349
Balance after adoption of ASU 2016-13
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 4,467	$ 4,461
Balance at end of period			$ 4,461