Loans Receivable - Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	$ 3,928	$ 2,146
Cumulative effect adjustment resulting from changes in accounting principles	8,719	8,719
Provision for expected credit losses	4,791	6,930
Allowance for expected credit losses at June 30, 2020	8,719	8,719
Real estate loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	1,435	1,502
Cumulative effect adjustment resulting from changes in accounting principles	4,318	4,318
Provision for expected credit losses	2,883	3,721
Allowance for expected credit losses at June 30, 2020	4,318	4,318
Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	2,493	644
Cumulative effect adjustment resulting from changes in accounting principles	4,401	4,401
Provision for expected credit losses	1,908	3,209
Allowance for expected credit losses at June 30, 2020	$ 4,401	4,401
Cumulative effect adjustment resulting from changes in accounting principles
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020		(357)
Cumulative effect adjustment resulting from changes in accounting principles		(357)
Cumulative effect adjustment resulting from changes in accounting principles | Real estate loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020		(905)
Cumulative effect adjustment resulting from changes in accounting principles		(905)
Cumulative effect adjustment resulting from changes in accounting principles | Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020		548
Cumulative effect adjustment resulting from changes in accounting principles		$ 548