Allowance for Credit Losses (Portfolio Credit Quality) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Loan portfolio by credit quality indicator
2020	$ 717,547
2019	2,893,624
2018	1,543,032
2017	857,320
2016	446,578
Prior	566,279
Total loans	7,024,380	$ 6,894,946
Pass
Loan portfolio by credit quality indicator
Total loans		6,538,085
Special Review
Loan portfolio by credit quality indicator
Total loans		33,553
Watch List - Pass
Loan portfolio by credit quality indicator
Total loans		62,315
Watch List - Substandard
Loan portfolio by credit quality indicator
Total loans		248,318
Commercial
Loan portfolio by credit quality indicator
2020	308,273
2019	607,918
2018	271,101
2017	145,503
2016	22,273
Prior	13,943
Total loans	1,369,011	1,292,660
Commercial | Pass
Loan portfolio by credit quality indicator
2020	245,351
2019	533,082
2018	270,142
2017	145,268
2016	22,269
Prior	13,917
Total loans	1,230,029	1,228,110
Commercial | Special Review
Loan portfolio by credit quality indicator
2019	71,700
Total loans	71,700	569
Commercial | Watch List - Pass
Loan portfolio by credit quality indicator
2019	11
Prior	26
Total loans	37	39
Commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
2020	62,569
2019	2,517
2018	504
2017	6
Total loans	65,596	62,007
Commercial | Watch List - Doubtful
Loan portfolio by credit quality indicator
2020	353
2019	608
2018	455
2017	229
2016	4
Total loans	1,649
Real estate - construction
Loan portfolio by credit quality indicator
2020	145,173
2019	1,148,594
2018	624,992
2017	238,744
2016	41,681
Prior	17,556
Total loans	2,216,740	2,185,883
Real estate - construction | Pass
Loan portfolio by credit quality indicator
2020	136,898
2019	1,064,250
2018	624,498
2017	238,744
2016	41,536
Prior	17,556
Total loans	2,123,482	2,090,370
Real estate - construction | Special Review
Loan portfolio by credit quality indicator
2019	16,106
Total loans	16,106	18,721
Real estate - construction | Watch List - Pass
Loan portfolio by credit quality indicator
2020	8,000
2019	35,622
2018	370
Total loans	43,992	41,949
Real estate - construction | Watch List - Substandard
Loan portfolio by credit quality indicator
2020	275
2019	31,804
2016	145
Total loans	32,224	33,905
Real estate - construction | Watch List - Doubtful
Loan portfolio by credit quality indicator
2019	812
2018	124
Total loans	936
Commercial Real Estate: Farmland and Commercial
Loan portfolio by credit quality indicator
2020	158,433
2019	734,400
2018	392,599
2017	206,499
2016	221,895
Prior	219,539
Total loans	1,933,365	1,896,747
Commercial Real Estate: Farmland and Commercial | Pass
Loan portfolio by credit quality indicator
2020	139,114
2019	675,730
2018	385,302
2017	203,811
2016	132,509
Prior	215,389
Total loans	1,751,855	1,710,446
Commercial Real Estate: Farmland and Commercial | Special Review
Loan portfolio by credit quality indicator
2020	938
2018	4,649
2017	175
2016	3,205
Prior	421
Total loans	9,388	13,184
Commercial Real Estate: Farmland and Commercial | Watch List - Pass
Loan portfolio by credit quality indicator
2020	16,713
2019	5,956
2018	2,648
2017	124
2016	587
Prior	1
Total loans	26,029	20,183
Commercial Real Estate: Farmland and Commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
2020	1,668
2019	52,471
2017	2,348
2016	85,594
Prior	3,495
Total loans	145,576	151,726
Commercial Real Estate: Farmland and Commercial | Watch List - Doubtful
Loan portfolio by credit quality indicator
2019	243
2017	41
Prior	233
Total loans	517
Commercial Real Estate: Multifamily
Loan portfolio by credit quality indicator
2020	10,764
2019	58,886
2018	38,954
2017	64,640
2016	14,660
Prior	14,546
Total loans	202,450	190,430
Commercial Real Estate: Multifamily | Pass
Loan portfolio by credit quality indicator
2020	10,623
2019	58,886
2018	38,954
2017	64,640
2016	14,660
Prior	14,535
Total loans	202,298	190,265
Commercial Real Estate: Multifamily | Watch List - Doubtful
Loan portfolio by credit quality indicator
2020	141
Prior	11
Total loans	152
Residential First Lien
Loan portfolio by credit quality indicator
2020	27,913
2019	75,150
2018	89,250
2017	65,513
2016	41,203
Prior	132,559
Total loans	431,588	433,901
Residential First Lien | Pass
Loan portfolio by credit quality indicator
2020	27,821
2019	75,150
2018	88,482
2017	65,513
2016	40,903
Prior	132,027
Total loans	429,896	426,546
Residential First Lien | Special Review
Loan portfolio by credit quality indicator
2016	249
Total loans	249	253
Residential First Lien | Watch List - Pass
Loan portfolio by credit quality indicator
2018	144
Total loans	144	144
Residential First Lien | Watch List - Substandard
Loan portfolio by credit quality indicator
2018	624
2016	51
Total loans	675	680
Residential First Lien | Watch List - Doubtful
Loan portfolio by credit quality indicator
2020	92
Prior	532
Total loans	624
Residential Junior Lien
Loan portfolio by credit quality indicator
2020	33,344
2019	161,204
2018	105,315
2017	128,460
2016	100,080
Prior	158,201
Total loans	686,604	706,476
Residential Junior Lien | Pass
Loan portfolio by credit quality indicator
2020	33,344
2019	161,204
2018	105,315
2017	127,651
2016	100,080
Prior	158,201
Total loans	685,795	704,958
Residential Junior Lien | Special Review
Loan portfolio by credit quality indicator
2017	809
Total loans	809	826
Consumer
Loan portfolio by credit quality indicator
2020	10,732
2019	28,354
2018	3,613
2017	558
2016	172
Prior	2,011
Total loans	45,440	47,800
Consumer | Pass
Loan portfolio by credit quality indicator
2020	10,732
2019	28,354
2018	3,613
2017	558
2016	172
Prior	2,008
Total loans	45,437	46,605
Consumer | Watch List - Doubtful
Loan portfolio by credit quality indicator
Prior	3
Total loans	3
Foreign
Loan portfolio by credit quality indicator
2020	22,915
2019	79,118
2018	17,208
2017	7,403
2016	4,614
Prior	7,924
Total loans	139,182	141,049
Foreign | Pass
Loan portfolio by credit quality indicator
2020	22,915
2019	79,118
2018	17,208
2017	7,403
2016	4,614
Prior	7,924
Total loans	$ 139,182	$ 140,785