Mergers and Acquisitions - Acquisition date fair value of purchased assets and liabilities (Details) - USD ($) $ in Thousands	May 01, 2019	Feb. 01, 2018	Nov. 01, 2017	Jul. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Assets
Accrued interest receivable					$ 32,660	$ 35,413
Net deferred tax asset					203
Liabilities
Total identifiable net assets					52,100	130,000			$ 115,000
Consideration transferred
Goodwill					$ 327,425	$ 307,112			$ 220,591
FMBT
Assets
Cash and cash equivalents	$ 32,548
Loans, net	192,494
Allowance for loan losses	0
Premises and equipment, net	8,524
Bank owned life insurance	6,823
Net deferred tax asset	157
Intangibles	2,800
Other assets	1,278
Total assets acquired	244,624
Liabilities
Deposits	212,127
Other liabilities	717
Total liabilities assumed	212,844
Total identifiable net assets	31,780
Consideration transferred
Cash	52,093
Goodwill	20,313
FMBT | Fair Value Adjustments
Assets
Cash and cash equivalents	0
Loans, net	(5,188)
Allowance for loan losses	6,338
Premises and equipment, net	1,400
Bank owned life insurance	0
Net deferred tax asset	(1,229)
Intangibles	2,800
Other assets	246
Total assets acquired	4,367
Liabilities
Deposits	243
Other liabilities	(207)
Total liabilities assumed	36
Aggregate fair value adjustments	4,331
FMBT | First Madison Bank & Trust | As Recorded by FMBT
Assets
Cash and cash equivalents	32,548
Loans, net	197,682
Allowance for loan losses	(6,338)
Premises and equipment, net	7,124
Bank owned life insurance	6,823
Net deferred tax asset	1,386
Intangibles	0
Other assets	1,032
Total assets acquired	240,257
Liabilities
Deposits	211,884
Other liabilities	924
Total liabilities assumed	212,808
Excess of assets acquired over liabilities assumed	$ 27,449
Navitas
Assets
Cash and cash equivalents		$ 27,700
Loans, net		358,352
Premises and equipment, net		324
Net deferred tax asset		2,873
Other assets		4,051
Total assets acquired		393,300
Liabilities
Short-term borrowings		214,923
Long-term debt		119,402
Other liabilities		16,108
Total liabilities assumed		350,433
Total identifiable net assets		42,867
Consideration transferred
Cash		84,500
Common stock issued		$ 45,746
Common stock issued (in shares)		1,443,987
Total fair value of consideration transferred		$ 130,246
Goodwill		87,379
Navitas | Fair Value Adjustments
Assets
Cash and cash equivalents		0
Loans, net		(7,181)
Premises and equipment, net		(304)
Net deferred tax asset		2,873
Other assets		(1,066)
Total assets acquired		(5,678)
Liabilities
Short-term borrowings		0
Long-term debt		0
Other liabilities		(951)
Total liabilities assumed		(951)
Aggregate fair value adjustments		(4,727)
Navitas | NLFC Holdings Corp | As Recorded by Navitas
Assets
Cash and cash equivalents		27,700
Loans, net		365,533
Premises and equipment, net		628
Net deferred tax asset		0
Other assets		5,117
Total assets acquired		398,978
Liabilities
Short-term borrowings		214,923
Long-term debt		119,402
Other liabilities		17,059
Total liabilities assumed		351,384
Excess of assets acquired over liabilities assumed		$ 47,594
FOFN
Assets
Cash and cash equivalents			$ 48,658
Securities			114,972
Loans held for sale			10,686					$ 10,700
Loans, net			486,244
Premises and equipment, net			12,398
Bank owned life insurance			20,339
Accrued interest receivable			1,740
Net deferred tax asset			17,334
Intangibles			8,738
Other real estate owned			659
Other assets			8,723
Total assets acquired			730,491
Liabilities
Deposits			565,205
Federal Home Loan Bank advances			65,224
Long-term debt			19,747
Other liabilities			7,390
Total liabilities assumed			657,566
Total identifiable net assets			72,925
Consideration transferred
Cash			12,802
Common stock issued			$ 113,665
Common stock issued (in shares)			4,145,343
Total fair value of consideration transferred			$ 126,467
Goodwill			53,542
FOFN | Fair Value Adjustments
Assets
Cash and cash equivalents			6
Securities			782
Loans held for sale			(3,290)
Loans, net			(5,477)
Premises and equipment, net			1,147
Bank owned life insurance			0
Accrued interest receivable			(118)
Net deferred tax asset			(999)
Intangibles			8,738
Other real estate owned			(514)
Other assets			(69)
Total assets acquired			206
Liabilities
Deposits			1,365
Federal Home Loan Bank advances			224
Long-term debt			(4,125)
Other liabilities			60
Total liabilities assumed			(2,476)
Aggregate fair value adjustments			2,682
FOFN | Four Oaks Bank | As Recorded by FOFN
Assets
Cash and cash equivalents			48,652
Securities			114,190
Loans held for sale			13,976
Loans, net			491,721
Premises and equipment, net			11,251
Bank owned life insurance			20,339
Accrued interest receivable			1,858
Net deferred tax asset			18,333
Intangibles			0
Other real estate owned			1,173
Other assets			8,792
Total assets acquired			730,285
Liabilities
Deposits			563,840
Federal Home Loan Bank advances			65,000
Long-term debt			23,872
Other liabilities			7,330
Total liabilities assumed			660,042
Excess of assets acquired over liabilities assumed			$ 70,243
HCSB
Assets
Cash and cash equivalents				$ 17,853
Securities				101,320
Loans, net				215,947
Premises and equipment, net				7,424			$ 7,420
Bank owned life insurance				11,827
Accrued interest receivable				1,047
Net deferred tax asset				25,579
Intangibles				5,716
Other real estate owned				805
Other assets				1,918
Total assets acquired				389,436
Liabilities
Deposits				318,942
Repurchase agreements				1,141
Federal Home Loan Bank advances				24,517
Other liabilities				2,046
Total liabilities assumed				346,646
Total identifiable net assets				42,790
Consideration transferred
Cash				31
Common stock issued				$ 65,800
Common stock issued (in shares)				2,370,331
Total fair value of consideration transferred				$ 65,831
Equity interest held before the business combination				1,125
Goodwill				24,166
HCSB | Fair Value Adjustments
Assets
Cash and cash equivalents				(2)
Securities				(142)
Loans, net				(12,536)
Premises and equipment, net				(6,606)
Bank owned life insurance				0
Accrued interest receivable				(275)
Net deferred tax asset				25,579
Intangibles				5,716
Other real estate owned				(372)
Other assets				(32)
Total assets acquired				11,330
Liabilities
Deposits				430
Repurchase agreements				0
Federal Home Loan Bank advances				517
Other liabilities				91
Total liabilities assumed				1,038
Aggregate fair value adjustments				10,292
HCSB | Horry County State Bank | As Recorded by HCSB
Assets
Cash and cash equivalents				17,855
Securities				101,462
Loans, net				228,483
Premises and equipment, net				14,030
Bank owned life insurance				11,827
Accrued interest receivable				1,322
Net deferred tax asset				0
Intangibles				0
Other real estate owned				1,177
Other assets				1,950
Total assets acquired				378,106
Liabilities
Deposits				318,512
Repurchase agreements				1,141
Federal Home Loan Bank advances				24,000
Other liabilities				1,955
Total liabilities assumed				345,608
Excess of assets acquired over liabilities assumed				$ 32,498