CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
OPERATING ACTIVITIES:
Net income	$ 26,697	$ 29,516
Adjustments to reconcile net income to net cash provided by operating activities:
Net accretion (amortization) on investment securities	330	(8)
Net accretion on loans and amortization of core deposit intangible and operating lease components	(799)	(596)
Unrealized (gains) losses on equity securities with readily determinable fair value	381	(289)
Depreciation of premises and equipment	2,549	2,263
Amortization of mortgage servicing rights	585	322
Impairment of mortgage servicing rights	100
Credit loss expense for on-balance sheet exposures	22,760	17,231
Credit loss expense for off-balance sheet exposures	102
Net gain on sale of mortgage loans held for sale	(4,805)	(1,260)
Origination of mortgage loans held for sale	(125,273)	(40,714)
Proceeds from sale of mortgage loans held for sale	109,918	39,632
Net gain on sale of consumer loans held for sale	(2,337)	(1,405)
Origination of consumer loans held for sale	(195,121)	(146,087)
Proceeds from sale of consumer loans held for sale	194,182	147,466
Net gain realized on sale of other real estate owned	(3)	(130)
Impairment of premises held for sale		66
Deferred compensation expense - Class A Common Stock	222	233
Stock-based awards expense - Class A Common Stock	280	244
Net gain on sale of bank premises and equipment	(353)
Increase in cash surrender value of bank owned life insurance	(389)	(382)
Net change in other assets and liabilities:
Accrued interest receivable	900	(28)
Accrued interest payable	635	536
Other assets	(7,381)	(2,026)
Other liabilities	4,998	(297)
Net cash provided by operating activities	28,178	44,287
INVESTING ACTIVITIES:
Purchases of available-for-sale debt securities	(138,894)
Proceeds from calls, maturities and paydowns of available-for-sale debt securities	73,716	48,775
Proceeds from calls, maturities and paydowns of held-to-maturity debt securities	690	600
Net change in outstanding warehouse lines of credit	(132,996)	(90,092)
Net change in other loans	50,510	(63,922)
Proceeds from redemption of Federal Home Loan Bank stock	931	2,102
Purchase of Federal Home Loan Bank stock	(9,000)
Proceeds from sales of other real estate owned	31	229
Proceeds from sale of bank premises and equipment	894
Net purchases of premises and equipment	(1,109)	(1,036)
Net cash used in investing activities	(155,227)	(103,344)
FINANCING ACTIVITIES:
Net change in deposits	285,449	318,171
Net change in securities sold under agreements to repurchase and other short-term borrowings	(41,537)	(9,822)
Payments of Federal Home Loan Bank advances	(602,500)	(520,000)
Proceeds from Federal Home Loan Bank advances	425,000	270,000
Repurchase of Class A Common Stock	(2,852)	(379)
Net proceeds from Class A Common Stock purchased through employee stock purchase plan	155	121
Net proceeds from Class A Common Stock options exercised and PSUs awarded	(242)
Cash dividends paid	(5,464)	(4,996)
Net cash provided by financing activities	58,009	53,095
NET CHANGE IN CASH AND CASH EQUIVALENTS	(69,040)	(5,962)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	385,303	351,474
CASH AND CASH EQUIVALENTS AT END OF PERIOD	316,263	345,512
Cash paid during the period for:
Interest	7,786	9,798
Income taxes	465	387
SUPPLEMENTAL NONCASH DISCLOSURES:
Transfers from loans to real estate acquired in settlement of loans		155
Right-of-use assets recorded	626	$ 40,104
Allowance for credit losses recorded upon adoption of ASC 326	$ 7,241