Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net income	$ 175,892	$ 83,651	$ 167,596
Adjustments to reconcile net income to net cash provided by operating activities:
(Recovery of) provision for credit losses	(1,668)	86,850	7,050
Depreciation, amortization and accretion	47,350	34,633	8,185
Deferred income tax expense (benefit)	11,411	(13,662)	20,041
Funding of mortgage loans held for sale	(4,059,927)	(4,479,421)	(2,381,178)
Proceeds from sales of mortgage loans held for sale	4,116,106	4,530,328	2,328,607
Gains on sales of mortgage loans held for sale	(82,399)	(150,406)	(45,854)
Valuation adjustment to mortgage servicing rights	(13,561)	11,726	1,836
Gains on sales of securities	(2,170)	(46)	(348)
Debt prepayment penalty	6,123	121	54
(Gains) losses on sales of premises and equipment	(840)	38	(881)
Stock-based compensation	10,074	10,577	10,196
Net change in other loans held for sale	0	0	59,885
(Increase) decrease in other assets	(20,812)	(59,224)	683
(Decrease) increase in other liabilities	(42,920)	27,077	(12,249)
Net cash provided by operating activities	142,659	82,242	163,623
Investing activities
Purchases of securities available for sale	(2,107,934)	(515,657)	(492,018)
Proceeds from sales of securities available for sale	176,455	44,906	212,485
Proceeds from call/maturities of securities available for sale	458,020	437,981	262,287
Purchases of securities held to maturity	(52,135)	0	0
Proceeds from call/maturities of securities held to maturity	2,246	0	0
Net decrease (increase) in loans	910,063	(1,233,232)	(465,182)
Purchases of premises and equipment	(20,516)	(28,270)	(34,966)
Proceeds from sales of premises and equipment	9,813	0	3,728
Purchase of bank-owned life insurance	(50,000)	0	0
Net change in FHLB stock	3,980	18,840	(11,315)
Proceeds from sales of other assets	6,342	8,438	18,404
Net cash paid in acquisition	0	0	(250)
Other, net	3,663	1,446	917
Net cash used in investing activities	(660,003)	(1,265,548)	(505,910)
Financing activities
Net increase in noninterest-bearing deposits	1,033,076	1,133,278	233,064
Net increase (decrease) in interest-bearing deposits	813,567	712,781	(147,139)
Net (decrease) increase in short-term borrowings	(7,393)	(467,872)	101,385
Proceeds from long-term debt	197,061	98,266	150,000
Repayment of long-term debt	(202,873)	(171)	(35,359)
Cash paid for dividends	(50,017)	(50,134)	(50,901)
Repurchase of shares in connection with stock repurchase program	(21,315)	(24,569)	(62,944)
Net cash provided by financing activities	1,762,106	1,401,579	188,106
Net increase (decrease) in cash and cash equivalents	1,244,762	218,273	(154,181)
Cash and cash equivalents at beginning of year	633,203	414,930	569,111
Cash and cash equivalents at end of year	1,877,965	633,203	414,930
Supplemental disclosures
Cash paid for interest	45,745	73,686	98,396
Cash paid for income taxes	50,977	39,989	26,727
Noncash transactions:
Transfers of loans to other real estate	3,180	8,588	4,764
Financed sales of other real estate owned	577	148	611
Recognition of operating right-of-use assets	8,142	9,393	91,181
Recognition of operating lease liabilities	8,142	9,393	94,700
Available for sale securities transferred to held to maturity securities	366,886	0	0
Mortgage Receivable
Noncash transactions:
Transfers of mortgage loans held for sale to loans held for investment	0	0	189
Loans Receivable
Noncash transactions:
Transfers of mortgage loans held for sale to loans held for investment	$ 0	$ 0	$ 134,335