Income Taxes - Tax Effects of Temporary Differences Related to Deferred Taxes Included in Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deferred tax assets:
Loans acquired	$ 11,933	$ 20,783
Allowance for credit losses	59,918	16,732
Valuation of foreclosed assets	2,636	2,626
Tax NOLs from acquisition	16,165	18,118
Deferred compensation payable	3,009	2,750
Accrued equity and other compensation	7,179	6,677
Acquired securities	0	3,393
Right-of-use lease liability	8,230	10,221
Allowance for unfunded commitments	6,122	0
Other	6,004	7,886
Gross deferred tax assets	121,196	89,186
Deferred tax liabilities:
Goodwill and other intangible amortization	(39,495)	(41,221)
Accumulated depreciation	(36,731)	(36,554)
Right-of-use lease asset	(8,161)	(10,176)
Unrealized gain on available-for-sale securities	(12,321)	(3,720)
Deferred loan fees and costs	(2,696)	(3,018)
Acquired securities	(870)	0
Other	(4,972)	(4,633)
Gross deferred tax liabilities	(105,246)	(99,322)
Net deferred tax asset, included in other assets	$ 15,950
Deferred Tax Liabilities, Net		$ (10,136)