Loans Receivable and Allowance for Credit Losses (Amortized Cost of Loans on Nonaccrual Status) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	$ 151,785	$ 126,676
Commercial lending
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	135,927	110,096
Commercial lending | Commercial and industrial (“C&I”)
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	63,312	62,040
Commercial lending | Commercial real estate (“CRE”)
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	49,137	45,537
Commercial lending | Real estate loan | Multifamily residential
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	3,578	2,519
Commercial lending | Construction and land
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	19,900	0
Commercial lending | Total CRE
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	72,615	48,056
Consumer lending
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	15,858	16,580
Consumer lending | Real estate loan | Single-family residential
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	6,014	6,013
Consumer lending | HELOCs
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	7,353	8,076
Consumer lending | Total residential mortgage
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	13,367	14,089
Consumer lending | Other consumer
Financing Receivable, Nonaccrual [Line Items]
Total nonaccrual loans with no related allowance for loan losses	$ 2,491	$ 2,491