Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income	$ 161,441	$ 121,027	$ 73,548
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation	13,120	10,014	9,196
Net losses (gains) on sale or disposal of premises and equipment	41	133	1,264
Net write-downs on other assets	6,210	0	0
Provision for loan losses	19,758	16,667	8,364
Net write-downs and losses on sale of other real estate owned	496	1,301	500
Share-based compensation expense	3,424	6,241	3,316
Amortization of intangible assets	17,713	9,512	3,932
Amortization of operating lease right of use assets	10,264
Provision for deferred taxes	22,821	1,374	12,430
Net amortization of investment securities available for sale	4,680	4,891	6,384
Net loss (gain) on securities	(138)	37	(37)
Accretion of discount on purchased loans	(20,255)	(11,918)	(11,308)
Amortization of premium on purchased loan pools	1,277	1,825	3,543
Net amortization (accretion) on other borrowings	80	96	95
Amortization of subordinated deferrable interest debentures	1,655	1,345	1,322
Originations of mortgage loans held for sale	(3,791,311)	(1,768,934)	(1,502,314)
Payments received on mortgage loans held for sale	17,445	986	1,238
Proceeds from sales of mortgage loans held for sale	2,620,290	1,542,755	1,370,008
Net gains on mortgage loans held for sale	(74,546)	(37,336)	(46,913)
Originations of SBA loans	(41,435)	(27,820)	(33,104)
Proceeds from sales of SBA loans	65,862	33,675	30,696
Net gains on sales of SBA loans	(6,058)	(2,728)	(4,590)
Increase in cash surrender value of bank owned life insurance	(2,692)	(1,819)	(1,588)
Gain on bank owned life insurance proceeds	(3,583)	0	0
Loss on sale of loans	1,233	0	0
Changes in FDIC loss-share receivable/payable, net of cash payments received	3,865	5,156	3,005
Increase in interest receivable	(15,392)	(10,965)	(3,728)
Increase (decrease) in interest payable	5,855	2,411	1,757
Increase (decrease) in taxes payable	(3,597)	4,032	(473)
Change attributable to other operating activities	41,266	(10,761)	10,895
Net cash used in operating activities	(940,211)	(108,803)	(62,562)
Investing Activities, net of effects of business combinations
Proceeds from maturities of time deposits in other banks	10,563	746	0
Purchases of securities available for sale	(219,352)	(290,649)	(113,261)
Proceeds from prepayments and maturities of securities available for sale	266,171	152,393	115,166
Proceeds from sale of securities available for sale	64,995	68,727	3,090
Net decrease (increase) in other investments	(44,935)	33,515	11,046
Net increase in loans, excluding purchased loans	(1,934,070)	(470,156)	(1,016,409)
Payments received on purchased loans	1,015,798	330,226	210,470
Purchase of acquired formerly serviced portfolio	(103,530)	0	0
Payments received on purchased loan pools	48,140	71,817	112,330
Purchases of premises and equipment	(11,581)	(10,009)	(3,760)
Proceeds from sale of premises and equipment	5,587	588	16
Proceeds from sales of other real estate owned	10,140	11,784	14,920
Payments received from (paid to) FDIC under loss-sharing agreements	(3,710)	(3,791)	(515)
Proceeds from bank owned life insurance	7,429	0	0
Proceeds from sales of loans	157,087	0	0
Net cash proceeds received from (paid in) acquisitions	244,181	51,495	0
Net cash used in investing activities	(487,087)	(53,314)	(666,907)
Financing Activities, net of effects of business combinations
Net increase in deposits	334,437	853,051	1,050,682
Net decrease in securities sold under agreements to repurchase	(22,094)	(10,254)	(22,867)
Proceeds from other borrowings	5,236,572	1,530,000	1,837,692
Repayment of other borrowings	(4,141,349)	(1,844,258)	(2,079,554)
Issuance of common stock	0	0	88,656
Proceeds from exercise of stock options	5,139	914	2,669
Dividends paid - common stock	(24,675)	(16,405)	(14,650)
Purchase of treasury shares	(18,410)	(2,062)	(886)
Net cash provided by financing activities	1,369,620	510,986	861,742
Net increase (decrease) in cash and cash equivalents	(57,678)	348,869	132,273
Cash and cash equivalents at beginning of period	679,527	330,658	198,385
Cash and cash equivalents at end of period	621,849	679,527	330,658
Cash paid during the year for:
Interest	125,373	67,523	32,465
Income taxes	35,865	20,026	38,939
Loans (excluding purchased loans) transferred to other real estate owned	1,094	4,124	4,372
Purchased loans transferred to other real estate owned	5,135	6,393	5,023
Loans transferred from loans held for sale to loans held for investment	0	10,817	212,850
Loans transferred from loans held for investment to loans held for sale	8,293	8,831	119,389
Loans provided for the sales of other real estate owned	144	931	1,334
Initial recognition of operating lease right-of-use assets	27,286
Initial recognition of operating lease liabilities	29,651
Right-of-use assets obtained in exchange for new operating lease liabilities	6,016
Assets acquired in business combinations	5,194,955	3,064,615	0
Liabilities assumed in business combinations	4,325,642	2,415,212	0
Issuance of common stock in acquisitions	869,294	547,127	0
Issuance of common stock in exchange for equity investment in US Premium Finance Holding Company	0	0	5,844
Change in unrealized gain (loss) on securities available for sale, net of tax	23,320	(3,266)	(338)
Change in unrealized gain on cash flow hedge, net of tax	$ (499)	$ 112	$ 116