Loans and Leases (Recorded Fair Values of Purchased Non-Impaired Loans and Leases) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) loans	Dec. 31, 2017 USD ($) loans	May 05, 2017 USD ($)
Non-PCI Loans
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	491	632
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 43,553	$ 49,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	164	204
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 13,318	$ 11,990
Principal Forgiveness [Member] | Non-PCI Loans
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	3	6
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,003	$ 1,206
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 634
Principal Forgiveness [Member] | Non-PCI Loans | Commercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	3	5
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,003	$ 1,124
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 634
Principal Forgiveness [Member] | Non-PCI Loans | Noncommercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 82
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Extended Maturity [Member] | Non-PCI Loans
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	42	47
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 5,486	$ 6,517
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	8	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 865	$ 273
Extended Maturity [Member] | Non-PCI Loans | Commercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	21	13
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 3,933	$ 3,007
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	4	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 675	$ 0
Extended Maturity [Member] | Non-PCI Loans | Noncommercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	21	34
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,554	$ 3,510
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	4	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 190	$ 273
Interest Rate Below Market Reduction [Member] | Non-PCI Loans
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	269	363
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 28,404	$ 30,412
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	92	110
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 8,459	$ 7,983
Interest Rate Below Market Reduction [Member] | Non-PCI Loans | Commercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	85	92
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 12,859	$ 14,811
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	24	32
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 2,998	$ 3,392
Interest Rate Below Market Reduction [Member] | Non-PCI Loans | Noncommercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	184	271
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 15,545	$ 15,601
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	68	78
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 5,461	$ 4,591
Discharge of Debt [Member] | Non-PCI Loans
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	177	216
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 8,660	$ 10,865
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	64	91
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 3,994	$ 3,100
Discharge of Debt [Member] | Non-PCI Loans | Commercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	26	39
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 2,043	$ 3,012
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	8	26
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 825	$ 708
Discharge of Debt [Member] | Non-PCI Loans | Noncommercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	151	177
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 6,617	$ 7,853
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	56	65
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 3,169	$ 2,392
Palmetto Heritage Bancshares
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition	142,413
CertainLoansAcquiredinTransferNotAccountedforasDebtSecuritiesAcquiredDuringPeriodCashFlowsNotExpectedtobeCollectedatAcquisition	0
Total non-PCI loans and leases	131,283		$ 131,300
Palmetto Heritage Bancshares | Commercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			52,356
Palmetto Heritage Bancshares | Commercial | Construction and land development
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			13,186
Palmetto Heritage Bancshares | Commercial | Mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			29,225
Palmetto Heritage Bancshares | Commercial | Other commercial real estate
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			753
Palmetto Heritage Bancshares | Commercial | Commercial and industrial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			8,153
Palmetto Heritage Bancshares | Commercial | Other
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			1,039
Palmetto Heritage Bancshares | Noncommercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			78,927
Palmetto Heritage Bancshares | Noncommercial | Mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			59,076
Palmetto Heritage Bancshares | Noncommercial | Commercial and industrial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			11,103
Palmetto Heritage Bancshares | Noncommercial | Revolving mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			6,175
Palmetto Heritage Bancshares | Noncommercial | Consumer
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			2,573
Capital Commerce Bancorp
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition	198,568
CertainLoansAcquiredinTransferNotAccountedforasDebtSecuritiesAcquiredDuringPeriodCashFlowsNotExpectedtobeCollectedatAcquisition	5,427
Total non-PCI loans and leases	173,354		173,400
Capital Commerce Bancorp | Commercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			108,019
Capital Commerce Bancorp | Commercial | Construction and land development
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			10,299
Capital Commerce Bancorp | Commercial | Mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			57,049
Capital Commerce Bancorp | Commercial | Other commercial real estate
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			6,370
Capital Commerce Bancorp | Commercial | Commercial and industrial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			34,301
Capital Commerce Bancorp | Commercial | Other
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			0
Capital Commerce Bancorp | Noncommercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			65,335
Capital Commerce Bancorp | Noncommercial | Mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			50,630
Capital Commerce Bancorp | Noncommercial | Commercial and industrial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			11,173
Capital Commerce Bancorp | Noncommercial | Revolving mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			2,552
Capital Commerce Bancorp | Noncommercial | Consumer
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			980
HomeBancorp Inc.
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition	710,876
CertainLoansAcquiredinTransferNotAccountedforasDebtSecuritiesAcquiredDuringPeriodCashFlowsNotExpectedtobeCollectedatAcquisition	9,845
Total non-PCI loans and leases	550,618		550,600
HomeBancorp Inc. | Commercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			252,327
HomeBancorp Inc. | Commercial | Construction and land development
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			525
HomeBancorp Inc. | Commercial | Mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			188,688
HomeBancorp Inc. | Commercial | Other commercial real estate
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			55,183
HomeBancorp Inc. | Commercial | Commercial and industrial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			7,931
HomeBancorp Inc. | Commercial | Other
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			0
HomeBancorp Inc. | Noncommercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			298,291
HomeBancorp Inc. | Noncommercial | Mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			296,273
HomeBancorp Inc. | Noncommercial | Commercial and industrial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			0
HomeBancorp Inc. | Noncommercial | Revolving mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			51
HomeBancorp Inc. | Noncommercial | Consumer
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			1,967
Guaranty Bank
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition	703,916
CertainLoansAcquiredinTransferNotAccountedforasDebtSecuritiesAcquiredDuringPeriodCashFlowsNotExpectedtobeCollectedatAcquisition	16,073
Total non-PCI loans and leases	$ 574,553		574,600
Guaranty Bank | Commercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			185,249
Guaranty Bank | Commercial | Construction and land development
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			0
Guaranty Bank | Commercial | Mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			850
Guaranty Bank | Commercial | Other commercial real estate
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			0
Guaranty Bank | Commercial | Commercial and industrial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			583
Guaranty Bank | Commercial | Other
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			183,816
Guaranty Bank | Noncommercial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			389,304
Guaranty Bank | Noncommercial | Mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			309,612
Guaranty Bank | Noncommercial | Commercial and industrial
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			0
Guaranty Bank | Noncommercial | Revolving mortgage
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			54,780
Guaranty Bank | Noncommercial | Consumer
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total non-PCI loans and leases			$ 24,912