Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash Flows from Operating Activities:
Net income	$ 100,328	$ 97,577
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for (recovery of) credit losses	20,601	(1,222)
Depreciation	6,407	6,950
Amortization of discounts and premiums, net	6,384	1,195
Net gain on sales of securities	(534)	(5,409)
Gain on trading activity		(35)
Net loss on sales of loans	4	10
Stock-based compensation	8,251	7,910
Deferred tax expense	44,465	2,811
Changes in operating assets and liabilities:
Increase in other assets	(34,397)	15,797
Decrease in other liabilities	(20,813)	32,818
Purchases of securities held for trading		(22,500)
Proceeds from sales of securities held for trading		22,535
Net cash provided by operating activities	130,696	158,437
Cash Flows from Investing Activities:
Proceeds from repayment of securities available for sale	428,098	316,103
Proceeds from sales of securities available for sale	369,972	272,849
Purchase of securities available for sale	(483,789)	(655,425)
Redemption of Federal Home Loan Bank stock	72,567	58,643
Purchases of Federal Home Loan Bank stock	(88,875)	(2,250)
Proceeds from bank-owned life insurance, net	1,772	2,664
Proceeds from sales of loans	3,124	29,326
Purchases of loans	(26,300)
Other changes in loans, net	(380,427)	(391,409)
Purchase of premises and equipment, net	(438)	1,946
Net cash provided by (used in) investing activities	(104,296)	(367,553)
Cash Flows from Financing Activities:
Net increase in deposits	315,634	836,695
Net increase in short-term borrowed funds	1,350,000
Proceeds from long-term borrowed funds	2,150,000	749,820
Repayments of long-term borrowed funds	(3,125,000)	(1,700,000)
Cash dividends paid on common stock	(79,332)	(79,340)
Cash dividends paid on preferred stock	(8,207)	(8,207)
Treasury stock repurchased	(28,924)	(67,125)
Payments relating to treasury shares received for restricted stock award tax payments	(8,235)	(7,663)
Net cash provided by (used in) financing activities	565,936	(275,820)
Net increase (decrease) in cash, cash equivalents, and restricted cash	592,336	(484,936)
Cash, cash equivalents, and restricted cash at beginning of period	741,870	1,474,955
Cash, cash equivalents, and restricted cash at end of period	1,334,206	990,019
Supplemental information:
Cash paid for interest	202,459	187,890
Cash paid for income taxes	10,000	5,908
Non-cash investing and financing activities:
Transfers to repossessed assets from loans	120	2,840
Operating lease liabilities arising from obtaining right-of-use assets as of January 1, 2019		324,360
Securitization of residential mortgage loans to mortgage-backed securities available for sale	26,300
Transfer of loans from held for investment to held for sale	3,124	29,336
Dispositions of premises and equipment		1,245
Shares issued for restricted stock awards	$ 22,198	$ 15,058