Allowance for Probable Loan Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	$ 8,292	$ 40,674
Past due	94,889	75,833
Loans, current	6,612,454	6,485,456
Total loans	6,707,343	6,561,289
30 to 59 Days
Financing receivable recorded investment
Past due	30,159	15,978
60 to 89 Days
Financing receivable recorded investment
Past due	11,883	6,011
90 Days or Greater
Financing receivable recorded investment
Past due	52,847	53,844
Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	844	10,890
Past due	27,278	25,591
Loans, current	1,186,261	1,103,378
Total loans	1,213,539	1,128,969
Commercial \| 30 to 59 Days
Financing receivable recorded investment
Past due	7,139	4,651
Commercial \| 60 to 89 Days
Financing receivable recorded investment
Past due	1,412	1,089
Commercial \| 90 Days or Greater
Financing receivable recorded investment
Past due	18,727	19,851
Commercial Real Estate:Other Construction and Land Development
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,041	16
Past due	10,427	3,356
Loans, current	1,923,919	1,882,875
Total loans	1,934,346	1,886,231
Commercial Real Estate:Other Construction and Land Development \| 30 to 59 Days
Financing receivable recorded investment
Past due	7,451	727
Commercial Real Estate:Other Construction and Land Development \| 60 to 89 Days
Financing receivable recorded investment
Past due	1,111	1,707
Commercial Real Estate:Other Construction and Land Development \| 90 Days or Greater
Financing receivable recorded investment
Past due	1,865	922
Commercial Real Estate: Farmland and Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	401	24,910
Past due	37,106	30,951
Loans, current	1,859,552	1,918,947
Total loans	1,896,658	1,949,898
Commercial Real Estate: Farmland and Commercial \| 30 to 59 Days
Financing receivable recorded investment
Past due	6,486	2,928
Commercial Real Estate: Farmland and Commercial \| 60 to 89 Days
Financing receivable recorded investment
Past due	5,292	784
Commercial Real Estate: Farmland and Commercial \| 90 Days or Greater
Financing receivable recorded investment
Past due	25,328	27,239
Commercial Real Estate: Multifamily
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing		71
Past due	2,567	1,505
Loans, current	291,545	224,752
Total loans	294,112	226,257
Commercial Real Estate: Multifamily \| 30 to 59 Days
Financing receivable recorded investment
Past due	1,122	927
Commercial Real Estate: Multifamily \| 60 to 89 Days
Financing receivable recorded investment
Past due	938
Commercial Real Estate: Multifamily \| 90 Days or Greater
Financing receivable recorded investment
Past due	507	578
Residential First Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	4,272	3,079
Past due	9,638	9,037
Loans, current	447,276	436,763
Total loans	456,914	445,800
Residential First Lien \| 30 to 59 Days
Financing receivable recorded investment
Past due	3,610	3,998
Residential First Lien \| 60 to 89 Days
Financing receivable recorded investment
Past due	1,516	1,677
Residential First Lien \| 90 Days or Greater
Financing receivable recorded investment
Past due	4,512	3,362
Residential Junior Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,574	937
Past due	3,536	2,881
Loans, current	717,576	724,420
Total loans	721,112	727,301
Residential Junior Lien \| 30 to 59 Days
Financing receivable recorded investment
Past due	982	1,155
Residential Junior Lien \| 60 to 89 Days
Financing receivable recorded investment
Past due	815	618
Residential Junior Lien \| 90 Days or Greater
Financing receivable recorded investment
Past due	1,739	1,108
Consumer
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	16	32
Past due	449	550
Loans, current	45,624	45,766
Total loans	46,073	46,316
Consumer \| 30 to 59 Days
Financing receivable recorded investment
Past due	351	486
Consumer \| 60 to 89 Days
Financing receivable recorded investment
Past due	73	19
Consumer \| 90 Days or Greater
Financing receivable recorded investment
Past due	25	45
Foreign
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	144	739
Past due	3,888	1,962
Loans, current	140,701	148,555
Total loans	144,589	150,517
Foreign \| 30 to 59 Days
Financing receivable recorded investment
Past due	3,018	1,106
Foreign \| 60 to 89 Days
Financing receivable recorded investment
Past due	726	117
Foreign \| 90 Days or Greater
Financing receivable recorded investment
Past due	$ 144	$ 739

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

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Financing receivables that are current.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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