Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Income after income tax expense	$ 125,109	$ 53,816
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	20,556	96,943
Share-based compensation expense	7,277	5,647
Depreciation and amortization	106,381	99,541
Provision (benefit) for deferred income taxes	46,452	(3,016)
Net gains on sales of assets	(24,365)	(28,573)
Proceeds from sales of loans and leases held-for-sale	525,556	268,133
Originations of loans and leases held-for-sale, net of repayments	(399,628)	(362,680)
Loan servicing rights (recovery) impairment	(7,637)	8,236
Net change in other assets	(138,828)	(218,094)
Net change in other liabilities	(143,062)	(405,718)
Other, net	(1,073)	(14,106)
Net cash provided by (used in) operating activities	116,738	(499,871)
Cash flows from investing activities
Proceeds from maturities of and principal collected on investment securities available-for-sale	704,304	311,531
Purchases of investment securities available-for-sale	(858,934)	(412,011)
Proceeds from maturities of and principal collected on investment securities held-to-maturity	9,865	4,152
Purchases of investment securities held-to-maturity	(20,051)	0
Redemption of Federal Home Loan Bank stock	136,002	144,000
Purchases of Federal Home Loan Bank stock	(174,000)	(186,000)
Proceeds from sales of loans and leases	67,791	287,050
Loan and lease originations and purchases, net of principal collected	(961,317)	(1,717,733)
Proceeds from sales of other assets	28,114	16,494
Purchases of premises and equipment and lease equipment	(25,304)	(23,846)
Net cash paid in business combination	(1,069,830)	0
Other, net	(1,732)	15,177
Net cash used in investing activities	(2,165,092)	(1,561,186)
Cash flows from financing activities
Net change in deposits	930,495	1,143,905
Net change in short-term borrowings	808,720	813,425
Proceeds from long-term borrowings	2,857,651	4,150,000
Payments on long-term borrowings	(2,710,221)	(3,912,310)
Repurchases of common stock	0	(33,098)
Dividends paid on preferred stock	(2,493)	(2,493)
Dividends paid on common stock	(53,704)	(53,578)
Exercise of stock options	(327)	63
Payments related to tax-withholding upon conversion of share-based awards	(738)	(2,289)
Net investment by (distribution to) non-controlling interest	7,680	7,932
Net cash provided by financing activities	1,837,063	2,111,557
Net change in cash and due from banks	(211,291)	50,500
Cash and cash equivalents at beginning of period	1,260,595	1,228,371
Cash and cash equivalents at end of period	1,049,304	1,278,871
Cash paid for:
Interest on deposits and borrowings	34,454	76,688
Income taxes, net	4,971	1,838
Noncash activities:
Transfer of loans and leases to other assets	8,143	15,983
Transfer of loans and leases from held-for-investment to held for sale, net	$ 48,210	$ 251,855