Fair Value Measurements - Fair Value Measurements - Valuation Methodology and Unobservable Inputs for Level 3 Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)		Dec. 31, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 63,865		$ 28,811
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	60,834		27,728
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	3,031		1,083
Non Purchased Credit Impaired Loans and Leases
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	63,865	[1]	28,706	[2]
Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	60,834	[1]	27,623	[2]
Non Purchased Credit Impaired Loans and Leases | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	3,031	[1]	1,083	[2]
Other real estate and foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value			105
Other real estate and foreclosed assets | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value			105
Other real estate and foreclosed assets | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value			$ 0
Discount Rates | Discounted Cash Flow | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	26,357
Discount From Appraisals | Third party appraisals | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	26,889
No Discounts | Third party appraisals | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 7,588
Measurement Input, Discount Rate | Minimum | Discounted Cash Flow | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	0.0375
Measurement Input, Discount Rate | Maximum | Discounted Cash Flow | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	0.1046
Measurement Input, Discount Rate | Discount Rates | Weighted Average | Discounted Cash Flow | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	0.0819
Measurement Input, Discount Rate | Discount From Appraisals | Minimum | Third party appraisals | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	0.2300
Measurement Input, Discount Rate | Discount From Appraisals | Maximum | Third party appraisals | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	0.2300
Measurement Input, Discount Rate | Discount From Appraisals | Weighted Average | Third party appraisals | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	0.2300

[1] Includes nonaccrual loans and leases and performing TDRs with balances greater than $250,000.

[2] Includes all nonaccrual loans and leases and performing TDRs.