Premises and Equipment and Lease Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 442,117	$ 405,452
Accumulated depreciation and amortization	(152,116)	(131,520)
Property, Plant and Equipment, Net	290,001	273,932
Depreciation and amortization expense	$ 22,800	$ 22,100	$ 21,500
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Right of Use Assets [Abstract]
Operating Lease, Right-of-Use Asset	$ 83,647	$ 79,574
Finance Lease, Right-of-Use Asset	1,770	1,996
Total right-of-use assets	85,417	81,570
Lease Liabilities [Abstract]
Operating Lease, Liability	87,737	83,219
Finance Lease, Liability	3,001	3,244
Total lease liabilities	90,738	86,463
Lease, Cost [Abstract]
Operating Lease, Cost	13,963	13,992
Short-term Lease, Cost	354	295
Finance Lease, Interest Expense	227	243
Amortization of right-of-use asset	226	226
Sublease Income	(1,324)	(1,463)
Net lease cost	13,446	13,293
Operating cash flows related to operating leases	13,494	13,609
Financing cash flows related to finance leases	227	243
Finance Lease, Principal Payments	$ 243	$ 226
Weighted average remaining lease term
Operating leases	10 years 4 months 13 days	10 years 9 months
Finance leases	7 years 10 months 2 days	8 years 10 months 2 days
Weighted average discount rate
Operating leases	2.91%	3.07%
Finance leases	7.22%	7.22%
Operating Leases
2021	$ 13,607
2022	12,413
2023	11,582
2024	11,506
2025	9,247
Thereafter	45,701
Total	104,056
Less: Imputed Interest	(16,319)
Net lease liabilities	87,737	$ 83,219
Finance Leases
2021	470
2022	470
2023	479
2024	527
2025	527
Thereafter	1,494
Total	3,967
Less: Imputed Interest	(966)
Net lease liabilities	3,001	3,244
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	70,140	64,814
Building
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 194,432	185,340
Building | Minimum
Property, Plant and Equipment [Line Items]
Range of Useful Lives	15 years
Building | Maximum
Property, Plant and Equipment [Line Items]
Range of Useful Lives	30 years
Leaseholds and Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 50,867	45,398
Leaseholds and Leasehold Improvements | Minimum
Property, Plant and Equipment [Line Items]
Range of Useful Lives	15 years
Leaseholds and Leasehold Improvements | Maximum
Property, Plant and Equipment [Line Items]
Range of Useful Lives	20 years
Furniture and Equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 126,678	$ 109,900
Furniture and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Range of Useful Lives	3 years
Furniture and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Range of Useful Lives	20 years