Premises, Equipment and Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Premises and Equipment [Abstract]
Premises and equipment before accumulated depreciation	$ 180,197	$ 179,910
Accumulated depreciation	105,991	104,279
Total premises and equipment	74,206	75,631
Operating lease ROU assets	$ 26,400	$ 34,800
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Net Lease Cost [Abstract]
Operating lease cost	$ 7,382	$ 7,239
Variable lease cost	2,141	2,231
Short-term lease cost	453	356
Sublease income	(502)	(448)
Total premises and equipment	9,474	9,378
Future Minimum Rental Commitments Related to Non-cancelable Operating Leases [Abstract]
2021	7,209
2022	6,339
2023	5,251
2024	4,581
2025	3,411
Thereafter	10,023
Total lease payments	36,814
Less: interest	(3,990)
Present value of lease liabilities	$ 32,824	$ 37,300
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Additional Information Related to Operating Leases [Abstract]
Weighted average remaining lease term, in years	7 years 2 months 15 days	7 years 8 months 8 days
Weighted average discount rate	3.02%	3.00%
Cash paid for amounts included in the measurement of lease liabilities [Abstract]
Operating cash flows from operating leases	$ 7,934	$ 6,211
ROU assets obtained in exchange for lease liabilities	3,441	41,008
Rental expense	8,000	8,000	$ 8,600
Land, Buildings and Improvements [Member]
Premises and Equipment [Abstract]
Premises and equipment before accumulated depreciation	125,002	121,479
Equipment [Member]
Premises and Equipment [Abstract]
Premises and equipment before accumulated depreciation	$ 55,195	$ 58,431
Equipment [Member] | Minimum [Member]
Premises and Equipment [Abstract]
Property, plant and equipment, useful life	3 years
Equipment [Member] | Maximum [Member]
Premises and Equipment [Abstract]
Property, plant and equipment, useful life	10 years
Building and Improvements [Member] | Minimum [Member]
Premises and Equipment [Abstract]
Property, plant and equipment, useful life	5 years
Building and Improvements [Member] | Maximum [Member]
Premises and Equipment [Abstract]
Property, plant and equipment, useful life	20 years