Loans Receivable and Allowance for Credit Losses - (Narrative for Credit Risk Ratings and/or Vintage Years for Loans Held-for-Investment by Portfolio Segment) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) loan
HELOCs
Financing Receivable, Credit Quality Indicator [Line Items]
Amount converted to loans	$ 145.0
C&I
Financing Receivable, Credit Quality Indicator [Line Items]
Amount converted to loans	$ 23.9
Number of converted loans | loan	4