Loans and Allowance for Loan Losses - Summary of Aging of Loans (Parenthetical) (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loan premiums	$ 5,251	$ 5,758
Capitalized loan origination costs	20,656	$ 18,403
Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans granted deferred status under CARES Act	$ 80,403