CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES:
Net income	$ 91,699	$ 77,852	$ 45,632
Adjustments to reconcile net income to net cash provided by operating activities:
Net amortization on investment securities	(120)	97	245
Net accretion on loans and amortization of core deposit intangible and operating lease components	(3,655)	(3,540)	(6,373)
Unrealized (gains) losses on equity securities with readily determinable fair value	(382)	122
Depreciation of premises and equipment	9,230	9,347	8,472
Amortization of mortgage servicing rights	1,823	1,432	1,504
Provision for loan and lease losses	25,758	31,368	27,704
Net gain on sale of mortgage loans held for sale	(8,816)	(3,839)	(3,977)
Origination of mortgage loans held for sale	(356,097)	(176,916)	(160,091)
Proceeds from sale of mortgage loans held for sale	354,660	177,545	169,969
Net gain on sale of consumer loans held for sale	(5,102)	(5,930)	(5,647)
Origination of consumer loans held for sale	(710,640)	(778,476)	(663,171)
Proceeds from sale of consumer loans held for sale	716,336	781,951	661,098
Net realized losses on debt securities			136
Net gain realized on sale of other real estate owned	(540)	(729)	(831)
Writedowns of other real estate owned			155
Impairment of premises held for sale	256	482	1,175
Deferred compensation expense - Class A Common Stock	584	645	191
Stock-based awards expense - Class A Common Stock	1,035	1,001	1,142
Net gain on sale of banking center	(7,829)
Net gain on sale of bank premises and equipment	(339)	14
Increase in cash surrender value of bank owned life insurance	(1,550)	(1,527)	(1,562)
Net change in other assets and liabilities:
Accrued interest receivable	1,031	(1,860)	(1,726)
Accrued interest payable	1,718	(16)	152
Other assets	(8,677)	2,822	730
Other liabilities	(3,138)	7,368	2,850
Net cash provided by operating activities	97,245	119,213	77,777
INVESTING ACTIVITIES:
Net cash provided from branch divestiture	6,071
Purchases of available-for-sale debt securities	(445,681)	(173,875)	(225,212)
Purchases of held-to-maturity debt securities		(4,934)	(15,595)
Proceeds from calls, maturities and paydowns of available-for-sale debt securities	455,823	220,798	158,056
Proceeds from calls, maturities and paydowns of held-to-maturity debt securities	2,667	3,911	4,207
Proceeds from sales of available-for-sale debt securities	0	0	20,012
Net change in outstanding warehouse lines of credit	(248,763)	56,877	59,867
Purchase of non-business-acquisition loans, including premiums paid			(6,160)
Net change in other loans	(188,708)	(216,600)	(268,839)
Proceeds from redemption of Federal Home Loan Bank stock	3,513
Purchase of Federal Home Loan Bank stock	(2,277)		(3,859)
Proceeds from sales of other real estate owned	2,063	1,346	2,793
Proceeds from sale of bank premises and equipment	909	764
Net purchases of premises and equipment	(12,883)	(9,822)	(12,383)
Net cash used in investing activities	(427,266)	(121,535)	(287,113)
FINANCING ACTIVITIES:
Net change in deposits	461,715	22,987	272,466
Net change in securities sold under agreements to repurchase and other short-term borrowings	(15,373)	(21,031)	30,548
Payments of Federal Home Loan Bank advances	(820,000)	(457,500)	(490,000)
Proceeds from Federal Home Loan Bank advances	760,000	530,000	425,000
Repurchase of Class A Common Stock	(1,418)	(827)	(1,048)
Net proceeds from Class A Common Stock purchased through employee stock purchase plan	494	230
Net proceeds from Class A Common Stock options exercised	(191)	83	68
Cash dividends paid	(21,377)	(19,497)	(17,656)
Net cash provided by financing activities	363,850	54,445	219,378
NET CHANGE IN CASH AND CASH EQUIVALENTS	33,829	52,123	10,042
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	351,474	299,351	289,309
CASH AND CASH EQUIVALENTS AT END OF PERIOD	385,303	351,474	299,351
Cash paid during the period for:
Interest	43,039	30,139	20,106
Income taxes	17,383	11,119	28,779
SUPPLEMENTAL NONCASH DISCLOSURES:
Transfers from loans to real estate acquired in settlement of loans	1,527	662	841
Transfers from loans held for sale to held for investment		2,237
Loans provided for sales of other real estate owned	51
Transfers from loans held for investment to held for sale	131,881	1,392
Unfunded commitments in low-income-housing investments	11,500	$ 14,029	$ 9,736
Right-of-use assets recorded	$ 41,726