Loans - Secured Loans Distributed within California (Details) - USD ($)		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 55,099,000	$ 74,080,000	$ 86,203,000
Loans - percent		100.00%	100.00%
San Francisco [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal	[1]	$ 17,694,000	$ 29,659,000
Loans - percent	[1]	32.10%	40.00%
San Mateo [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal	[1]	$ 7,696,000	$ 16,756,000
Loans - percent	[1]	14.00%	22.60%
Alameda [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal	[1]	$ 6,239,000	$ 823,000
Loans - percent	[1]	11.30%	1.10%
Santa Clara [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal	[1]	$ 4,600,000	$ 4,600,000
Loans - percent	[1]	8.40%	6.20%
Marin [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal	[1]	$ 1,653,000	$ 917,000
Loans - percent	[1]	3.00%	1.20%
Sonoma [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal	[1]	$ 576,000	$ 0
Loans - percent	[1]	1.00%	0.00%
Contra Costa [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal	[1]	$ 0	$ 302,000
Loans - percent	[1]	0.00%	0.40%
San Francisco Bay Area [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal	[1]	$ 38,458,000	$ 53,057,000
Loans - percent	[1]	69.80%	71.50%
Mariposa [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 56,000	$ 46,000
Loans - percent		0.10%	0.10%
Placer [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 0	$ 1,500,000
Loans - percent		0.00%	2.00%
Santa Cruz [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 0	$ 485,000
Loans - percent		0.00%	0.70%
Amador [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 0	$ 701,000
Loans - percent		0.00%	0.90%
Other Northern California [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 56,000	$ 2,732,000
Loans - percent		0.10%	3.70%
Northern California [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 38,514,000	$ 55,789,000
Loans - percent		69.90%	75.20%
Los Angeles [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 10,783,000	$ 10,199,000
Loans - percent		19.60%	13.80%
Orange [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 2,192,000	$ 642,000
Loans - percent		4.00%	0.90%
Santa Barbara [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 2,062,000	$ 2,070,000
Loans - percent		3.70%	2.80%
Riverside [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 460,000	$ 0
Loans - percent		0.80%	0.00%
San Diego [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 1,088,000	$ 0
Loans - percent		2.00%	0.00%
Los Angeles And Coastal [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 16,125,000	$ 12,911,000
Loans - percent		29.30%	17.50%
San Bernardino [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal			$ 5,380,000
Loans - percent		0.00%	7.30%
Other Southern California [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 460,000	$ 5,380,000
Loans - percent		0.80%	7.30%
Southern California [Member]
Loans (Details) - Secured Loans by Property Type [Line Items]
Secured loans, principal		$ 16,585,000	$ 18,291,000
Loans - percent		30.10%	24.80%

[1] Includes Silicon Valley