Loans Receivable and Allowance for Credit Losses (Summary of COVID-19 Impact) (Details) - USD ($) $ in Thousands	Apr. 20, 2021	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans		$ 9,803,536	$ 9,822,890
First 90-day Deferral Period | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 300
Second 90-Day Deferral Period, Expected To Be Granted | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	46,600
Completed Deferral Period | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	85,100
Loans In Deferral, Total Amount | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	123,500
Principal Only Deferral | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 119,000
Percentage of total loans	96.40%
Hotel | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 40,900
Multifamily | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	33,100
Retail Properties | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	8,600
Restaurants | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	6,500
Residential | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	8,500
Payment Deferral | Maximum | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 1,310,000
Percentage of total loans	16.80%
Payment Deferral | Minimum | Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 132,000
Percentage of total loans	1.30%