Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 91,157	$ 88,354	$ 116,143	$ 107,737
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of investment premiums, net	1,106			4,455
Gain on sale of investment securities, net	(2)			(4)
Provision for credit losses	4,804			0
Change in cash surrender value of bank owned life insurance	(2,122)			(2,105)
Depreciation, amortization and accretion	7,613			7,759
Gain on sale of premises and equipment	(571)			(149)
Additions to residential mortgage servicing rights carried at fair value	(7,390)			(14,065)
Change in fair value of residential mortgage servicing rights carried at fair value	(34,802)			6,559
Stock-based compensation	2,454			2,964
Net increase in equity and other investments	(413)			(400)
Loss on equity securities, net	2,661			706
Gain on sale of loans and leases, net	(4,458)			(50,194)
Change in fair value of loans held for sale	11,055			24,118
Origination of loans held for sale	(649,122)			(1,635,532)
Proceeds from sales of loans held for sale	683,347			1,837,626
Change in other assets and liabilities:
Net decrease in other assets	167,911			128,221
Net increase (decrease) in other liabilities	2,097			(25,683)
Net cash provided by operating activities	275,325			392,013
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of investment securities available for sale	(131,869)			(555,269)
Proceeds from investment securities available for sale	126,011			227,122
Redemption of restricted equity securities	28			19,615
Net change in loans and leases	(470,337)			(267,940)
Proceeds from sales of loans and leases	44,549			82,529
Change in premises and equipment	(3,736)			(4,007)
Proceeds from bank owned life insurance death benefits	1,111			2,708
Other	104			129
Net cash used in investing activities	(434,139)			(495,113)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in deposit liabilities	104,906			1,264,645
Net increase in securities sold under agreements to repurchase	7,292			45,018
Repayment of borrowings	0			(490,000)
Dividends paid on common stock	(45,532)			(46,248)
Repurchase and retirement of common stock	(4,037)			(2,315)
Net cash provided by financing activities	62,629			771,100
Net (decrease) increase in cash and cash equivalents	(96,185)			668,000
Cash and cash equivalents, beginning of period	2,761,621		$ 3,241,181	2,573,181
Cash and cash equivalents, end of period	2,665,436	$ 2,761,621		3,241,181
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest	7,667			15,434
Income taxes	6,051			36,404
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Changes in unrealized gains and losses on investment securities available for sale, net of taxes	(176,079)			(64,883)
Changes in unrealized gains and losses on junior subordinated debentures carried at fair value, net of taxes	(9,436)			(19,730)
Transfer of loans held for sale to loans	$ 0			$ 212,353