Recent Accounting Pronouncements (Additional Information) (Details) $ in Thousands	Jan. 01, 2020 USD ($) segment	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) segment	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Accounting Policies [Abstract]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net reduction of retained earnings upon adoption of ASC 326		$ (603,981)	$ (594,674)	$ (583,540)	$ (573,820)	$ (562,927)	$ (499,411)	$ (479,187)	$ (458,640)
Allowance for credit losses	$ 31,931	46,768	42,431		$ 16,278	15,869	16,239		15,823
Number of loan segments | segment	8				6
Accrued interest receivable		14,995			$ 13,929
Impact of adopting ASC 326 - PCD Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses					405
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net reduction of retained earnings upon adoption of ASC 326		$ (272,579)	$ (263,011)	$ (253,780)	(253,090)	$ (241,801)	$ (233,269)	$ (222,246)	$ (211,424)
Impact of ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net reduction of retained earnings upon adoption of ASC 326					6,717
Allowance for credit losses	$ 15,653
Impact of ASC 326 Adoption | Impact of adopting ASC 326 - PCD Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	6,886				6,886
Impact of ASC 326 Adoption | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net reduction of retained earnings upon adoption of ASC 326	$ 6,717				$ 6,717