Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized (gains) losses included in net income, net of premium amortization	$ 0	$ 0
Impaired loans not covered under loss-share agreements	29,606,000	22,621,000
Specific reserve included in allowance for loan losses	52,162,000	49,026,000
Valuation adjustment to mortgage servicing rights	1,836,000	0	$ 0
Net gain (loss) resulting from fair value changes of these mortgage loans	1,286,000	4,892,000	$ 1,594,000
Impaired Loans, Not Covered
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Specific reserve included in allowance for loan losses	$ 2,258,000	$ 935,000