Consolidated Statement of Cash Flows (Statement) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss) Attributable to Parent	$ 127,923	$ 102,700	$ 110,387
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Provision for loan losses	12,054	6,171	7,945
Amortization of Deferred Loan Origination Fees, Net	21,598	6,826	6,158
Goodwill, Purchase Accounting Adjustments	(2,403)	(3,373)	(793)
Depreciation	10,814	9,119	8,585
Accretion (Amortization) of Discounts and Premiums, Investments	(1,362)	(1,455)	(1,262)
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Repayment and Penalties	10,529	612	197
Deferred Income Tax Expense (Benefit)	(4,525)	(844)	538
Gain (Loss) on Sale of Investments	3,286	(421)	(2,271)
Gain on equity securities, net	2,182	5,118	4,616
Share-based Payment Arrangement, Noncash Expense	7,272	6,324	5,063
Payments for Loan Originations, Loans to be Sold in Secondary Market	1,026,346	338,437	202,827
Proceeds From Loan Sales	1,031,227	340,637	207,836
Gain (Loss) on Sales of Loans, Net	0	0	2,826
Gains (Losses) on Sales of Other Real Estate	1,207	(222)	4,235
Bank Owned Life Insurance Income	4,789	4,557	6,815
Amortization Method Qualified Affordable Housing Project Investments, Amortization	7,046	6,927	7,322
Increase (Decrease) in Other Operating Assets and Liabilities, Net [Abstract]
Increase (Decrease) in Other Operating Assets	(9,216)	(12,530)	(9,904)
Increase (Decrease) in Other Operating Liabilities	(6,302)	(3,781)	5,131
Net Cash Provided by (Used in) Operating Activities, Total	111,646	111,626	131,994
Net Cash Provided by (Used in) Investing Activities [Abstract]
Payments for (Proceeds from) Federal Home Loan Bank Stock	(7,970)	(14,675)	(7,003)
Proceeds from Sale of Debt Securities	312,160	91,110	244,399
Proceeds from Sale, Maturity and Collection of Investments [Abstract]
Proceeds from Sale and Maturity of Held-to-maturity Securities	0	475	10,547
Proceeds from Sale and Maturity of Debt Securities, Available-for-sale	223,728	195,989	197,826
Payments to Acquire Investments [Abstract]
Payments to Acquire Held-to-maturity Securities	0	0	7,133
Payments to Acquire Debt Securities, Available-for-sale	354,299	0	373,372
Payments to Acquire Available-for-sale Securities, Equity	3,567	100	2,590
Payments to Acquire Federal Reserve Bank Stock	0	(6,428)	0
Increase (Decrease) in Equity Securities, FV-NI	(2,120)	(6,429)	(1,153)
Payments for (Proceeds from) Loans and Leases	620,200	216,353	57,315
Proceeds from Sale of Other Loans Held-for-sale	4,400	0	3,000
Proceeds from Sale of Other Real Estate	5,654	1,465	13,094
Proceeds from Life Insurance Policy	1,360	1,571	8,096
Payment to Acquire Life Insurance Policy, Investing Activities	0	(3,000)	0
Payments for Affordable Housing Programs	6,596	6,038	0
Payments to Acquire Property, Plant, and Equipment	28,632	14,885	11,533
Payments to Acquire Businesses, Net of Cash Acquired	0	4,831	(12,270)
Net Cash Provided by (Used in) Investing Activities, Total	(455,902)	60,079	45,445
Net Cash Provided by (Used in) Financing Activities [Abstract]
Increase (Decrease) in Deposits	1,230,073	159,696	159,590
(Increase) decrease in one way sell deposits	(710,101)	0	0
Proceeds from (Repayments of) Short-term Debt	111,573	(20,072)	(169,323)
Proceeds from Issuance of Long-term Debt	0	50,000	50,000
Proceeds from Issuance of Subordinated Long-term Debt	172,620	0	0
Repayments of Long-term Debt	170,529		150,197
Payments Related to Tax Withholding for Share-based Compensation	1,002	827	610
Payments for Repurchase of Common Stock	7,507	40,535	5,784
Payments of Ordinary Dividends	70,353	69,113	63,013
Net cash provided by (used in) financing activities	554,774	(178,963)	(179,337)
Cash and Cash Equivalents, Period Increase (Decrease), Total	210,518	(7,258)	(1,898)
Cash and Cash Equivalents, at Carrying Value, Beginning Balance	159,956	167,214	169,112
Cash and Cash Equivalents, at Carrying Value, Ending Balance	370,474	159,956	167,214
Supplemental Cash Flow Information [Abstract]
Interest Paid, Excluding Capitalized Interest, Operating Activities	29,157	63,038	43,600
Income Taxes Paid	24,260	15,186	7,345
Noncash Investing and Financing Items [Abstract]
Debt Securities, Held-to-maturity, Transfer, Amount	0	349,773	0
Real Estate Owned, Transfer to Real Estate Owned	1,790	1,671	1,204
Other Significant Noncash Transaction, Value of Consideration Received	7,821	11,475	0
Other repossessed assets, transfer to repossessed assets	0	0	11,379
Affordable Housing Program Obligation, Period Increase (Decrease)	10,000	10,000	8,000
Mortgages [Member]
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Gain (Loss) on Sale of Loans and Leases	24,269	7,198	4,879
Consumer Portfolio Segment [Member]
Increase (Decrease) in Other Operating Assets and Liabilities, Net [Abstract]
Increase (Decrease) in Prepaid Expense	$ (8,890)	$ (5,358)	$ (1,298)