Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income	$ 18,034,000	$ 51,448,000	$ 100,499,000
Adjustments to reconcile net income to net cash provided (used) by operating activities:
Depreciation and amortization	19,967,000	16,386,000	10,279,000
Provision for loan and lease losses	19,573,000	13,058,000	9,536,000
Amortization of premium on securities, net of accretion	507,000	802,000	460,000
Change in discount on unguaranteed loans	(9,270,000)	2,768,000	2,848,000
Impairment expense on goodwill and other intangibles, net	0	2,680,000	3,648,000
Deferred tax expense (benefit)	1,467,000	(5,936,000)	12,017,000
Originations of loans held for sale	(1,005,165,000)	(1,079,472,000)	(1,149,617,000)
Proceeds from sales of loans held for sale	457,533,000	1,086,614,000	883,366,000
Net gains on sale of loans held for sale	(29,002,000)	(75,170,000)	(78,590,000)
Net loss on sale of foreclosed assets	25,000	38,000	59,000
Gain on contribution to equity method investment			(68,000,000)
Net decrease (increase) in servicing assets	12,276,000	4,657,000	(304,000)
Gain on sale of securities available-for-sale	(620,000)
Net gain on sale or disposal of long lived asset	(357,000)
Net loss on disposal of premises and equipment	109,000	37,000	215,000
Equity method investments (income) loss	7,889,000	386,000	513,000
Equity security investments (gains) losses, net	(3,532,000)	(213,000)	(89,000)
Renewable energy tax credit investment impairment	602,000		690,000
Stock option based compensation expense	1,723,000	1,713,000	1,786,000
Restricted stock expense	10,025,000	7,463,000	5,717,000
Stock based compensation expense excess tax (shortfall) benefit	(125,000)	101,000	1,002,000
Business combination contingent consideration fair value adjustment		(260,000)	1,950,000
Changes in assets and liabilities:
Lease right-of-use assets, net	126,000
Other assets	394,000	(14,040,000)	(25,671,000)
Other liabilities	3,896,000	(1,539,000)	157,000
Net cash provided (used) by operating activities	(493,925,000)	11,521,000	(287,529,000)
Cash flows from investing activities
Purchases of securities available-for-sale	(253,100,000)	(347,184,000)	(43,071,000)
Proceeds from sales, maturities, calls, and principal paydowns of securities available-for-sale	111,290,000	56,631,000	19,693,000
Proceeds from sale/collection of foreclosed assets, net	796,000	527,000	1,498,000
Business combination, net of cash acquired			(7,696,000)
Sale of title insurance business, net of cash sold		(209,000)
Investment in certificates of deposit with other banks		(6,750,000)
Maturities of certificates of deposit with other banks		2,500,000	4,250,000
Loan and lease originations and principal collections, net	(505,848,000)	(445,643,000)	(385,551,000)
Proceeds from sale of long lived asset	10,895,000
Proceeds from sale of premises and equipment		865,000
Purchases of premises and equipment, net	(37,197,000)	(111,322,000)	(124,139,000)
Net cash used by investing activities	(673,164,000)	(850,585,000)	(535,016,000)
Cash flows from financing activities
Net increase in deposits	1,079,539,000	889,320,000	775,187,000
Proceeds from borrowings		18,000	40,000,000
Repayment of borrowings	(1,443,000)	(25,125,000)	(41,279,000)
Stock option exercises	508,000	1,626,000	1,026,000
Employee stock purchase program	437,000	342,000	445,000
Withholding cash issued in lieu of restricted stock	(409,000)	(756,000)	(4,891,000)
Sale of common stock, net of issuance costs			113,096,000
Shareholder dividend distributions	(4,827,000)	(4,809,000)	(3,776,000)
Net cash provided by financing activities	1,073,805,000	860,616,000	879,808,000
Net (decrease) increase in cash and cash equivalents	(93,284,000)	21,552,000	57,263,000
Cash and cash equivalents, beginning	316,823,000	295,271,000	238,008,000
Cash and cash equivalents, ending	223,539,000	316,823,000	295,271,000
Supplemental disclosure of cash flow information
Interest paid	87,280,000	54,106,000	25,390,000
Income tax (received) paid, net	(12,293,000)	1,750,000	7,084,000
Supplemental disclosures of noncash operating, investing, and financing activities
Unrealized holding gains (losses) on available-for-sale securities, net of taxes	13,401,000	(400,000)	(381,000)
Transfers from loans and leases to foreclosed real estate and other repossessions	5,058,000	346,000	1,406,000
Net transfers (to) from foreclosed real estate to SBA receivable	(281,000)	(32,000)	216,000
Transfer from fixed assets to other assets held for sale		10,467,000
Transfer of loans held for sale to loans and leases held for investment	277,964,000	131,266,000	63,643,000
Transfer of loans and leases held for investment to loans held for sale	39,067,000	94,154,000	19,534,000
Accrued premises and equipment additions	88,000	534,000
Loans to finance sale of other assets		$ 3,642,000
Right-of-use assets obtained in exchange for lessee operating lease liabilities	2,241,000
Equity method investment commitments	$ 16,282,000
Business combination:
Assets acquired (excluding goodwill)			5,766,000
Liabilities assumed			4,681,000
Purchase price			8,363,000
Goodwill recorded			$ 7,278,000