Fair Value of Financial Instruments - Schedule of Quantitative Information for Level 3 Fair Value Measurements (Details) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	$ 13,578,530	$ 8,691,019
Recurring | Level 3 | Black-Scholes option pricing model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants	$ 1,920
Recurring | Level 3 | Black-Scholes option pricing model | Volatility | Min
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.3000
Recurring | Level 3 | Black-Scholes option pricing model | Volatility | Max
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	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	0.3120
Recurring | Level 3 | Black-Scholes option pricing model | Risk free interest rate | Min
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.0013
Recurring | Level 3 | Black-Scholes option pricing model | Risk free interest rate | Max
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.0028
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	0.0017
Recurring | Level 3 | Black-Scholes option pricing model | Marketability Discount | Min
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	0.0600
Recurring | Level 3 | Black-Scholes option pricing model | Marketability Discount | Max
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity warrants, input	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	0.1348
Nonrecurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	$ 4,749	2,257
Nonrecurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, fair value	4,749	2,257
Total assets	4,749
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	$ 591	$ 569
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | CRE non-owner-occupied | Collateral discount and cost to sell | Min
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 | CRE non-owner-occupied | Collateral discount and cost to sell | Max
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 | CRE non-owner-occupied | Collateral discount and cost to sell | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000	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	$ 202	$ 408
Nonrecurring | Level 3 | Fair value of collateral | Investor loans secured by real estate | SBA secured by real estate | Collateral discount and cost to sell | Min
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 | Max
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	$ 230	$ 140
Nonrecurring | Level 3 | Fair value of collateral | Business loans secured by real estate | SBA secured by real estate | Collateral discount and cost to sell | Min
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000	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 | Max
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 | Collateral discount and cost to sell | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000	0.0781
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	$ 22
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Commercial and industrial | Collateral discount and cost to sell | Min
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Commercial and industrial | Collateral discount and cost to sell | Max
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	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	0.1000
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	$ 2,844
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | Franchise non-real estate secured | Collateral discount and cost to sell | Min
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 | Collateral discount and cost to sell | Max
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000
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	0.0911
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	$ 860	$ 1,140
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | SBA non-real estate secured | Collateral discount and cost to sell | Min
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.0700	0.0700
Nonrecurring | Level 3 | Fair value of collateral | Commercial loans | SBA non-real estate secured | Collateral discount and cost to sell | Max
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans receivable, input	0.1000	0.6300
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	0.0819	0.1533