Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net earnings	$ 172,624	$ 158,162
Depreciation and amortization	43,813	22,087
Provision for credit losses	34,043	22,963
(Gain) loss on sale of foreclosed assets	(534)	126
Provision for losses on foreclosed assets	0	406
Gain on sale of loans and leases	(633)	(163)
Gain on sale of premises and equipment	(23)	(11)
Gain on sale of securities	(8,588)	(3,089)
Unrealized gain on derivatives and foreign currencies, net	(569)	(1,226)
Earned stock compensation	11,600	8,074
Loss on sale of leasing unit	720	0
Tax effect included in stockholders' equity of restricted stock vesting	(3,683)	(401)
Decrease in accrued and deferred income taxes, net	68,466	72,169
(Increase) decrease in other assets	(2,388)	26,443
Decrease in accrued interest payable and other liabilities	(40,683)	(26,541)
Net cash provided by operating activities	274,165	278,999
Net Cash Provided by (Used in) Investing Activities [Abstract]
Net increase in loans and leases	(380,289)	(169,071)
Proceeds from sales of loans and leases	78,888	3,784
Proceeds from maturities and paydowns	117,684	63,741
Proceeds from sales	353,374	159,548
Purchases	(177,644)	(375,156)
Net (purchases) redemptions of Federal Home Loan Bank stock	(4,504)	23,359
Proceeds from sales of foreclosed assets	6,602	14,610
Purchases of premises and equipment, net	(3,951)	(3,407)
Proceeds from sales of premises and equipment	24	63
Proceeds from sale of leasing unit	138,955	0
Proceeds from BOLI death benefit	1,853	0
Net increase of equipment leased to others under operating leases	(16,060)	0
Net cash provided by (used in) investing activities	114,932	(282,529)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Noninterest-bearing	53,387	461,107
Interest-bearing	(569,414)	361,330
Net increase (decrease) in borrowings	298,324	(380,651)
Restricted stock surrendered	(4,416)	(8,336)
Tax effect included in stockholders' equity of restricted stock vesting	3,683	401
Cash dividends paid	(121,794)	(102,916)
Net cash (used in) provided by financing activities	(340,230)	330,935
Net increase in cash and cash equivalents	48,867	327,405
Cash and cash equivalents at beginning of period	396,486	313,226
Cash and cash equivalents at end of period	445,353	640,631
Noncash transactions from investing activities:
Cash paid for interest	28,558	29,006
Cash paid for income taxes	44,908	6,076
Loans transferred to foreclosed assets	$ 129	$ 3,089