Fair Value of Financial Instruments - Quantitative Information for Level 3 Fair Value Measurements (Details) $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	$ 14,121,193	$ 13,351,092
Recurring | Level 3 | Black-Scholes option pricing model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants	$ 1,895	$ 1,914
Recurring | Level 3 | Black-Scholes option pricing model | Volatility | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.3000	0.3000
Recurring | Level 3 | Black-Scholes option pricing model | Volatility | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.3500	0.3500
Recurring | Level 3 | Black-Scholes option pricing model | Volatility | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.3115	0.3119
Recurring | Level 3 | Black-Scholes option pricing model | Risk free interest rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.0019	0.0013
Recurring | Level 3 | Black-Scholes option pricing model | Risk free interest rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.0076	0.0036
Recurring | Level 3 | Black-Scholes option pricing model | Risk free interest rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.0032	0.0018
Recurring | Level 3 | Black-Scholes option pricing model | Marketability Discount | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.0550	0.0600
Recurring | Level 3 | Black-Scholes option pricing model | Marketability Discount | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.1600	0.1600
Recurring | Level 3 | Black-Scholes option pricing model | Marketability Discount | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.1359	0.1351
Nonrecurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	$ 9,348	$ 4,077
Nonrecurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	9,348	4,077
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | CRE non-owner-occupied
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	$ 7,045	$ 198
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | CRE non-owner-occupied | Collateral discount and cost to sell | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.0700	0.1000
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | CRE non-owner-occupied | Collateral discount and cost to sell | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.0700	0.1000
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | CRE non-owner-occupied | Collateral discount and cost to sell | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.0700	0.1000
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | SBA secured by real estate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	$ 976	$ 746
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | SBA secured by real estate | Collateral discount and cost to sell | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000	0.1000
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | SBA secured by real estate | Collateral discount and cost to sell | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000	0.1000
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | SBA secured by real estate | Collateral discount and cost to sell | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000	0.1000
Nonrecurring | Level 3 | Fair value of collateral | Business loans secured by real estate | SBA secured by real estate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value		$ 386
Nonrecurring | Level 3 | Fair value of collateral | Business loans secured by real estate | SBA secured by real estate | Collateral discount and cost to sell | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input		0.0700
Nonrecurring | Level 3 | Fair value of collateral | Business loans secured by real estate | SBA secured by real estate | Collateral discount and cost to sell | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input		0.1000
Nonrecurring | Level 3 | Fair value of collateral | Business loans secured by real estate | SBA secured by real estate | Collateral discount and cost to sell | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input		0.0909
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Commercial and industrial
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	$ 240	$ 2,040
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Commercial and industrial | Collateral discount and cost to sell | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.2000	0.0700
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Commercial and industrial | Collateral discount and cost to sell | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.2000	0.1000
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Commercial and industrial | Collateral discount and cost to sell | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.2000	0.0906
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | SBA non-real estate secured
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value		$ 707
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | SBA non-real estate secured | Collateral discount and cost to sell | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input		0.0700
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | SBA non-real estate secured | Collateral discount and cost to sell | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input		0.0700
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | SBA non-real estate secured | Collateral discount and cost to sell | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input		0.0700
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Franchise non-real estate secured
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	$ 1,087
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Franchise non-real estate secured | Collateral discount and cost to sell | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Franchise non-real estate secured | Collateral discount and cost to sell | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	1.0000
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Franchise non-real estate secured | Collateral discount and cost to sell | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1032