CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 504,350,000	$ 511,755,000
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Provision for loan losses	118,555,000	185,504,000
Amortization of intangibles	7,082,000	6,973,000
Depreciation and amortization of premises and equipment	42,928,000	39,083,000
Net accretion of discounts and amortization of premiums and deferred fees	(126,548,000)	(43,533,000)
Share-based compensation	11,418,000	5,962,000
Impairment losses on long-lived assets	2,591,000	272,000
Fair value adjustments on mortgage servicing rights	25,853,000	13,123,000
Goodwill, Impairment Loss		0
FDIC loss share expense	0	(94,725,000)
Adjustments (expense) to indemnity reserves on loans sold	1,664,000	6,482,000
Earnings from investments under the equity method, net of dividends or distributions	(18,461,000)	(14,772,000)
Deferred income tax expense	110,058,000	(97,708,000)
Gain on:
Disposition of premises and equipment and other productive assets	(5,133,000)	17,694,000
Proceeds from insurance claims	0	(14,411,000)
Sale of debt securities	(20,000)	0
Sale of loans, including valuation adjustments on loans held-for-sale and mortgage banking activities	(11,360,000)	(6,734,000)
Sale of foreclosed assets, including write-downs	(15,858,000)	(638,000)
Acquisitions of loans held-for-sale	(157,993,000)	(173,644,000)
Proceeds from sale of loans held-for-sale	51,067,000	51,131,000
Net originations on loans held-for-sale	(208,875,000)	(186,063,000)
Net decrease (increase) in:
Trading debt securities	333,013,000	346,455,000
Equity securities	(6,482,000)	(2,480,000)
Accrued income receivable	7,724,000	51,868,000
Other assets	(12,837,000)	234,836,000
Net (decrease) increase in:
Interest payable	(6,900,000)	(9,933,000)
Pension and other postretirement benefits obligation	(4,979,000)	3,392,000
Other liabilities	(102,049,000)	(197,035,000)
Total adjustments	34,498,000	121,099,000
Net cash provided by operating activities	538,848,000	632,854,000
Cash flows from investing activities:
Net decrease in money market investments	(1,000,840,000)	647,519,000
Purchases of investment securities:
Available-for-sale	(13,579,074,000)	(6,968,920,000)
Equity	(15,474,000)	(11,304,000)
Proceeds from calls, paydowns, maturities and redemptions of investment securities:
Available-for-sale	10,671,630,000	3,925,362,000
Held-to-maturity	5,325,000	7,184,000
Proceeds from sale of investment securities:
Available-for-sale	99,445,000	0
Equity	17,083,000	20,925,000
Net (disbursements) repayments on loans	(324,479,000)	(15,604,000)
Proceeds from sale of loans	77,327,000	1,354,000
Acquisition of loan portfolios	(421,482,000)	(461,117,000)
Payments to acquire other intangible	(793,000)	0
Net payments (to) from FDIC under loss sharing agreements	0	(25,012,000)
Payments to acquire businesses, net of cash acquired	0	(1,830,050,000)
Return of capital from equity method investments	2,747,000	2,501,000
Acquisition of premises and equipment	(45,961,000)	(53,144,000)
Proceeds from insurance claims	0	14,411,000
Proceeds from sale of:
Premises and equipment and other productive assets	17,186,000	6,991,000
Foreclosed assets	83,848,000	85,622,000
Net cash used in investing activities	(4,413,512,000)	(4,653,282,000)
Net increase (decrease) in:
Deposits	4,454,466,000	4,193,859,000
Assets sold under agreements to repurchase	(68,433,000)	(90,805,000)
Other short-term borrowings	(41,000)	(95,008,000)
Payments of notes payable	(144,991,000)	(226,976,000)
Principal payments of finance leases	(1,269,000)	0
Proceeds from issuance of notes payable	75,000,000	434,706,000
Proceeds from issuance of common stock	6,523,000	10,852,000
Dividends paid	(85,863,000)	(79,115,000)
Net payments for repurchase of common stock	(250,574,000)	(125,326,000)
Payments related to tax witholding for share-based compensation	(5,432,000)	(2,205,000)
Net cash provided by financing activities	3,979,386,000	4,019,982,000
Net (decrease) increase in cash and due from banks, and restricted cash	104,722,000	(446,000)
Cash and due from banks and restricted cash at beginning of period	403,251,000	412,629,000
Cash and due from banks and restricted cash at end of period	$ 507,973,000	$ 412,183,000