CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OPERATING ACTIVITIES:
Net income	$ 86,789,000	$ 83,246,000	$ 91,699,000
Adjustments to reconcile net income to net cash provided by operating activities:
Net amortization on investment securities and low-income housing investments	4,414,000	3,204,000	761,000
Net accretion on loans and amortization of core deposit intangible and operating lease components	(13,973,000)	(13,084,000)	(3,655,000)
Unrealized losses on equity securities with readily determinable fair value	463,000	105,000	(382,000)
Depreciation of premises and equipment	8,986,000	9,725,000	9,230,000
Amortization of mortgage servicing rights	3,453,000	3,756,000	1,823,000
(Recovery) impairment of mortgage servicing rights	(500,000)	500,000
Provision for on-balance sheet exposures	14,808,000	31,278,000	25,758,000
Provision for off-balance sheet exposures	63,000	533,000
Net gain on sale of mortgage loans held for sale	(19,659,000)	(33,179,000)	(8,816,000)
Origination of mortgage loans held for sale	(680,714,000)	(782,939,000)	(356,097,000)
Proceeds from sale of mortgage loans held for sale	717,847,000	788,475,000	354,660,000
Net gain on sale of consumer loans held for sale	(11,298,000)	(4,980,000)	(5,102,000)
Origination of consumer loans held for sale	(882,180,000)	(518,873,000)	(710,640,000)
Proceeds from sale of consumer loans held for sale	875,570,000	531,321,000	716,336,000
Net gain realized on sale of other real estate owned	(51,000)	(65,000)	(540,000)
Writedowns of other real estate owned	211,000	105,000
Impairment of premises held for sale			256,000
Deferred compensation expense - Class A Common Stock	1,024,000	918,000	584,000
Stock-based awards and ESPP expense - Class A Common Stock	1,545,000	953,000	1,035,000
Net gain on branch divestiture			(7,829,000)
Net gain on sale of bank premises and equipment	(399,000)	(353,000)	(339,000)
Increase in cash surrender value of bank owned life insurance	(2,242,000)	(1,585,000)	(1,550,000)
Death benefits in excess of cash surrender value of life insurance	(979,000)
FHLB advances early termination penalties		2,108,000
Net change in other assets and liabilities:
Accrued interest receivable	3,048,000	(14,000)	1,031,000
Accrued interest payable	(183,000)	(2,460,000)	1,718,000
Other assets	(940,000)	(19,391,000)	9,242,000
Other liabilities	(5,672,000)	(3,872,000)	(13,997,000)
Net cash provided by operating activities	99,431,000	75,432,000	105,186,000
INVESTING ACTIVITIES:
Net cash provided from branch divestiture			6,071,000
Purchases of available-for-sale debt securities	(211,545,000)	(298,878,000)	(445,681,000)
Proceeds from calls, maturities and paydowns of available-for-sale debt securities	230,457,000	251,930,000	455,823,000
Proceeds from calls, maturities and paydowns of held-to-maturity debt securities	9,139,000	9,009,000	2,667,000
Net change in outstanding warehouse lines of credit	112,246,000	(245,338,000)	(248,763,000)
Net change in other loans	207,115,000	(142,811,000)	(188,708,000)
Proceeds from redemption of Federal Home Loan Bank stock	7,086,000	22,434,000	3,513,000
Purchase of Federal Home Loan Bank stock		(9,000,000)	(2,277,000)
Proceeds from sales of other real estate owned	611,000	324,000	2,063,000
Proceeds from sale of bank premises and equipment	637,000	894,000	909,000
Purchase of bank owned life insurance, net of death benefits received	(28,901,000)
Investments in low-income housing tax partnerships	(14,507,000)	(6,998,000)	(7,941,000)
Net purchases of premises and equipment	(5,785,000)	(3,582,000)	(12,883,000)
Net cash provided by (used in) investing activities	306,553,000	(422,016,000)	(435,207,000)
FINANCING ACTIVITIES:
Net change in deposits	107,237,000	947,173,000	461,715,000
Net change in securities sold under agreements to repurchase and other short-term borrowings	79,941,000	43,409,000	(15,373,000)
Payments of Federal Home Loan Bank advances	(235,000,000)	(1,105,000,000)	(820,000,000)
Proceeds from Federal Home Loan Bank advances	25,000,000	590,000,000	760,000,000
FHLB advances early termination penalties		(2,108,000)
Payoff of subordinated note, net of common security interest	(40,000,000)
Repurchase of Class A Common Stock	(47,528,000)	(3,935,000)	(1,418,000)
Net proceeds from Class A Common Stock purchased through employee stock purchase plan	591,000	533,000	494,000
Net proceeds from option exercises and equity awards vested - Class A Common Stock	(142,000)		(191,000)
Cash dividends paid	(24,699,000)	(23,204,000)	(21,377,000)
Net cash (used in) provided by financing activities	(134,600,000)	446,868,000	363,850,000
NET CHANGE IN CASH AND CASH EQUIVALENTS	271,384,000	100,284,000	33,829,000
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	485,587,000	385,303,000	351,474,000
CASH AND CASH EQUIVALENTS AT END OF PERIOD	756,971,000	485,587,000	385,303,000
Cash paid during the period for:
Interest	5,849,000	22,403,000	43,039,000
Income taxes	20,069,000	24,926,000	17,383,000
SUPPLEMENTAL NONCASH DISCLOSURES:
Mortgage servicing rights capitalized	5,054,000	5,463,000	2,792,000
Transfers from loans to real estate acquired in settlement of loans	64,000	2,750,000	1,527,000
Loans provided for sales of other real estate owned			51,000
Transfers from loans held for investment to held for sale			131,881,000
Unfunded commitments in low-income-housing investments	10,000,000	10,000,000	18,800,000
Right-of-use assets recorded	$ 1,354,000	14,144,000	$ 41,726,000
Allowance for credit losses recorded upon adoption of ASC 326		$ 7,241,000