Allowance for Credit and Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 17,667	$ 55,090	$ 18,305	$ 17,667	$ 17,820
Initial PCD allowance	2,800			2,786
Provision for credit losses on loans		2,052	376	17,709	1,636
Charge–offs		(1,156)	(982)	(2,444)	(2,357)
Recoveries		333	257	810	857
Balance, end of period	22,577	56,319	17,956	56,319	17,956
Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	19,791			19,791
Balance, end of period	17,667
Mortgage warehouse
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,077	1,190	1,040	1,077	1,006
Initial PCD allowance				0
Provision for credit losses on loans		60	1	173	35
Charge–offs		0	0	0	0
Recoveries		0	0	0	0
Balance, end of period	0	1,250	1,041	1,250	1,041
Mortgage warehouse | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	0			0
Balance, end of period	1,077
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	11,996	39,147	11,881	11,996	10,495
Initial PCD allowance				2,786
Provision for credit losses on loans		1,136	393	14,655	2,105
Charge–offs		(502)	(224)	(586)	(640)
Recoveries		14	32	112	122
Balance, end of period		39,795	12,082	39,795	12,082
Commercial | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	10,832			10,832
Real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	923	5,832	1,732	923	1,676
Initial PCD allowance				0
Provision for credit losses on loans		(232)	(290)	670	(220)
Charge–offs		(144)	0	(204)	(48)
Recoveries		8	7	27	41
Balance, end of period		5,464	1,449	5,464	1,449
Real estate | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	4,048			4,048
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	3,671	8,921	3,652	3,671	4,643
Initial PCD allowance				0
Provision for credit losses on loans		1,088	272	2,211	(284)
Charge–offs		(510)	(758)	(1,654)	(1,669)
Recoveries		311	218	671	694
Balance, end of period		$ 9,810	$ 3,384	9,810	$ 3,384
Consumer | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 4,911			$ 4,911