Allowance for Loan Losses - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Minimum period interest and principal of loans past due considered nonperforming (in days)		90 days
Threshold for evaluation for impairment of substandard and nonaccrual commercial loans		$ 500
Increase in impaired loans		25,800
Impaired financing receivables		75,337	$ 49,506
Loans receivable, net		7,142,408	5,949,019
Modified loan	[1]	32,206	11,384
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans recorded investment		5,512,796	4,672,445
Modified loan		20,200
Commercial | Substandard
Financing Receivable, Allowance for Credit Loss [Line Items]
Increase (decrease) in loans		(28,500)
Loans recorded investment		152,651	181,192
Commercial | Special mention
Financing Receivable, Allowance for Credit Loss [Line Items]
Increase (decrease) in loans		16,500
Loans recorded investment		103,878	87,344
DNB
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans receivable, net		$ 899,300	$ 909,000

[1] Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.