Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Cash flows from operating activities:
Net earnings	$ 118,276		$ 78,668
Depreciation and amortization	8,751		8,496
Amortization of net premiums on securities available-for-sale	8,432		10,601
Amortization of intangible assets	6,346	$ 5,062	3,064
Provision for credit losses	4,000	6,406	24,728
Provision for losses on foreclosed assets	65		0
Gain on sale of loans and leases	(4,569)	(1,988)	(712)
Loss (gain) on sale of premises and equipment	7		(560)
(Gain) loss on sale of securities	(6,311)		99
Gain on BOLI death benefit	0		(471)
Unrealized (gain) loss on derivatives and foreign currencies, net	(605)		202
Earned stock compensation	7,199		6,470
Decrease in deferred income taxes, net	7,153		1,091
Decrease in other assets	38,208		661
(Decrease) increase in accrued interest payable and other liabilities	(50,969)		10,852
Net cash provided by operating activities	135,983		143,189
Cash flows from investing activities:
Net decrease (increase) in loans and leases	382,590		(157,244)
Proceeds from sales of loans and leases	615,376		37,173
Proceeds from maturities and paydowns of securities available-for-sale	75,125		92,612
Proceeds from sales of securities available-for-sale	306,253		42,996
Purchases of securities available-for-sale	(487,105)		(248,187)
Net redemptions of Federal Home Loan Bank stock	3,540		3,969
Proceeds from sales of foreclosed assets	28		212
Purchases of premises and equipment, net	(3,997)		(1,944)
Proceeds from sales of premises and equipment	0		10,290
Proceeds from BOLI death benefit	0		1,192
Net (increase) decrease in equipment leased to others under operating leases	(1,241)		114
Net cash provided by (used in) investing activities	890,569		(218,817)
Cash flows from financing activities:
Net (decrease) increase in noninterest-bearing deposits	(275,579)		131,170
Net (decrease) increase in interest-bearing deposits	(510,844)		329,605
Net increase (decrease) in borrowings	107,942		(445,203)
Early Repayment of Subordinated Debt	(12,372)		0
Common stock repurchased and restricted stock surrendered	(122,651)		(2,281)
Cash dividends paid	(63,689)		(60,833)
Net cash (used in) financing activities	(877,193)		(47,542)
Net increase (decrease) in cash, cash equivalents, and restricted cash	149,359		(123,170)
Cash, cash equivalents, and restricted cash, beginning of period	398,437		419,670
Cash, cash equivalents, and restricted cash, end of period	547,796	$ 398,437	296,500
Supplemental disclosures of cash flow information:
Cash paid for interest	17,515		14,352
Cash paid for income taxes	3,790		2,834
Loans transferred to foreclosed assets	$ 0		$ 78