Allowance for Credit Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	$ 53,198	$ 59,705
Past due	107,193	84,450
Loans, current	6,917,187	6,810,496
Total loans	7,024,380	6,894,946
30 to 59 Days
Financing receivable recorded investment
Past due	46,287	18,169
60 to 89 Days
Financing receivable recorded investment
Past due	6,285	4,937
90 Days or Greater
Financing receivable recorded investment
Past due	54,621	61,344
Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	997	421
Past due	6,951	5,052
Loans, current	1,362,060	1,287,608
Total loans	1,369,011	1,292,660
Commercial | 30 to 59 Days
Financing receivable recorded investment
Past due	4,226	3,134
Commercial | 60 to 89 Days
Financing receivable recorded investment
Past due	776	626
Commercial | 90 Days or Greater
Financing receivable recorded investment
Past due	1,949	1,292
Real estate - construction
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	145
Past due	10,577	564
Loans, current	2,206,163	2,185,319
Total loans	2,216,740	2,185,883
Real estate - construction | 30 to 59 Days
Financing receivable recorded investment
Past due	8,953	509
Real estate - construction | 60 to 89 Days
Financing receivable recorded investment
Past due	1,479	55
Real estate - construction | 90 Days or Greater
Financing receivable recorded investment
Past due	145
Commercial Real Estate: Farmland and Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	47,658	54,878
Past due	71,767	65,017
Loans, current	1,861,598	1,831,730
Total loans	1,933,365	1,896,747
Commercial Real Estate: Farmland and Commercial | 30 to 59 Days
Financing receivable recorded investment
Past due	22,566	8,058
Commercial Real Estate: Farmland and Commercial | 60 to 89 Days
Financing receivable recorded investment
Past due	1,543	2,031
Commercial Real Estate: Farmland and Commercial | 90 Days or Greater
Financing receivable recorded investment
Past due	47,658	54,928
Commercial Real Estate: Multifamily
Financing receivable recorded investment
Past due	135	478
Loans, current	202,315	189,952
Total loans	202,450	190,430
Commercial Real Estate: Multifamily | 30 to 59 Days
Financing receivable recorded investment
Past due	124	313
Commercial Real Estate: Multifamily | 90 Days or Greater
Financing receivable recorded investment
Past due	11	165
Residential First Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	3,164	3,107
Past due	9,676	8,559
Loans, current	421,912	425,342
Total loans	431,588	433,901
Residential First Lien | 30 to 59 Days
Financing receivable recorded investment
Past due	4,726	3,229
Residential First Lien | 60 to 89 Days
Financing receivable recorded investment
Past due	1,326	1,670
Residential First Lien | 90 Days or Greater
Financing receivable recorded investment
Past due	3,624	3,660
Residential Junior Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,173	1,200
Past due	3,195	2,789
Loans, current	683,409	703,687
Total loans	686,604	706,476
Residential Junior Lien | 30 to 59 Days
Financing receivable recorded investment
Past due	1,509	1,112
Residential Junior Lien | 60 to 89 Days
Financing receivable recorded investment
Past due	513	477
Residential Junior Lien | 90 Days or Greater
Financing receivable recorded investment
Past due	1,173	1,200
Consumer
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	60	88
Past due	943	630
Loans, current	44,497	47,170
Total loans	45,440	47,800
Consumer | 30 to 59 Days
Financing receivable recorded investment
Past due	717	467
Consumer | 60 to 89 Days
Financing receivable recorded investment
Past due	166	75
Consumer | 90 Days or Greater
Financing receivable recorded investment
Past due	60	88
Foreign
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1	11
Past due	3,949	1,361
Loans, current	135,233	139,688
Total loans	139,182	141,049
Foreign | 30 to 59 Days
Financing receivable recorded investment
Past due	3,466	1,347
Foreign | 60 to 89 Days
Financing receivable recorded investment
Past due	482	3
Foreign | 90 Days or Greater
Financing receivable recorded investment
Past due	$ 1	$ 11