Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Cash flows from operating activities:
Net earnings	$ 112,604		$ 118,276
Depreciation and amortization	9,287		8,751
Amortization of net premiums on securities available-for-sale	4,142		8,432
Amortization of intangible assets	4,870	$ 4,986	6,346
Amortization of ROU assets	7,608		0
Provision for credit losses	4,000	12,000	4,000
Gain on sale of foreclosed assets	(191)		0
Provision for losses on foreclosed assets	0		65
Gain on sale of loans and leases	0	0	(4,569)
Loss on sale of premises and equipment	3		7
Gain on sale of securities	(2,161)		(6,311)
Unrealized loss (gain) on derivatives and foreign currencies, net	16		(605)
Earned stock compensation	5,808		7,199
Decrease in deferred income taxes, net	14,714		7,153
Decrease in other assets	37,434		38,208
Decrease in accrued interest payable and other liabilities	(46,241)		(50,969)
Net cash provided by operating activities	151,893		135,983
Cash flows from investing activities:
Net (increase) decrease in loans and leases	(391,621)		382,590
Proceeds from sales of loans and leases	16,937		615,376
Proceeds from maturities and paydowns of securities available-for-sale	67,325		75,125
Proceeds from sales of securities available-for-sale	407,926		306,253
Purchases of securities available-for-sale	(402,030)		(487,105)
Net redemptions of Federal Home Loan Bank stock	2,673		3,540
Proceeds from sales of foreclosed assets	2,236		28
Purchases of premises and equipment, net	(5,625)		(3,997)
Net decrease in equipment leased to others under operating leases	(6,709)		(1,241)
Net cash (used in) provided by investing activities	(308,888)		890,569
Cash flows from financing activities:
Net decrease in noninterest-bearing deposits	(176,506)		(275,579)
Net increase (decrease) in interest-bearing deposits	591,932		(510,844)
Net increase in borrowings	109,973		107,942
Net decrease in subordinated debentures	0		(12,372)
Common stock repurchased and restricted stock surrendered	(124,109)		(122,651)
Cash dividends paid	(73,180)		(63,689)
Net cash provided by (used in) financing activities	328,110		(877,193)
Net increase in cash, cash equivalents, and restricted cash	171,115		149,359
Cash, cash equivalents, and restricted cash, beginning of period	385,767		398,437
Cash, cash equivalents, and restricted cash, end of period	556,882	$ 385,767	547,796
Supplemental disclosures of cash flow information:
Cash paid for interest	46,197		17,515
Cash paid for income taxes	2,778		3,790
Loans transferred to foreclosed assets	37		0
Transfers from loans held for investment to loans held for sale	$ 25,124		$ 0