Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Operating Activities:
Net income	$ 207,127	$ 204,729		$ 199,726
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	56,350	49,300		37,250
Deferred tax expense (benefit)	17,700	(15,513)		(5,154)
Depreciation and amortization	36,449	34,678		30,585
Amortization of earning assets and funding premium/discount, net	57,331	54,555		50,758
Stock-based compensation	11,438	10,935		10,223
Gain on sale, net of write-down, on foreclosed and repossessed assets	(976)	(311)		(1,297)
Loss (gain) on sale, net of write-down, on premises and equipment	397	(244)		(292)
Impairment loss on securities recognized in earnings	149	110		1,145
Gain on the sale of investment securities, net	(414)	(609)		(5,499)
Increase in cash surrender value of life insurance policies	(14,759)	(13,020)		(13,178)
Gain from life insurance policies	0	(220)		(2,229)
Mortgage banking activities	(11,103)	(7,795)		(4,070)
Proceeds from sale of loans held for sale	438,925	452,590		287,132
Originations of loans held for sale	(452,886)	(449,048)		(296,996)
Net decrease (increase) in derivative contract assets net of liabilities	27,929	(6,489)		(49,158)
Gain on redemption of other assets	(7,331)	0		0
Net decrease (increase) in accrued interest receivable and other assets	50,737	(44,334)	[1]	(2,552)	[1]
Net (decrease) increase in accrued expenses and other liabilities	(18,918)	33,478	[1]	6,601	[1]
Net cash provided by operating activities	398,145	302,792		242,995
Investing Activities:
Net decrease (increase) in interest-bearing deposits	126,446	(23,212)		(109,021)
Purchases of available-for-sale securities	(980,870)	(903,240)		(217,920)
Proceeds from maturities and principal payments of available-for-sale securities	672,965	558,301		416,821
Proceeds from sales of available-for-sale securities	259,283	123,270		98,402
Purchases of held-to-maturity securities	(1,066,156)	(761,033)		(1,113,958)
Proceeds from maturities and principal payments of held-to-maturity securities	795,953	681,124		575,009
Net (purchase) proceeds of Federal Home Loan Bank stock	(6,299)	4,943		(34,412)
Purchases of intercompany debt securities	(381)	458		(115)
Net increase in loans	(1,440,141)	(1,813,811)		(1,269,290)
Proceeds from loans not originated for sale	34,170	33,644		0
Purchase of life insurance policies	0	(50,000)		0
Proceeds from life insurance policies	0	3,912		2,178
Proceeds from the sale of foreclosed properties and repossessed assets	9,205	10,511		8,995
Proceeds from the sale of premises and equipment	1,550	650		3,565
Additions to premises and equipment	(40,731)	(36,115)		(30,039)
Acquisition of business, net cash acquired	0	1,396,414		0
Net cash used for investing activities	(1,635,006)	(774,184)		(1,669,785)
Financing Activities:
Net increase in deposits	1,351,609	853,921		797,244
Contingent consideration	5,000	0		0
Proceeds from Federal Home Loan Bank advances	19,630,000	13,505,000		10,372,226
Repayments of Federal Home Loan Bank advances	(19,451,219)	(13,700,279)		(9,565,192)
Net decrease in securities sold under agreements to repurchase and other borrowings	(201,874)	(99,356)		(80,906)
Issuance of long-term debt	0	0		150,000
Repayment of long-term debt	0	0		(150,000)
Debt issuance costs	0	0		(1,349)
Dividends paid to common shareholders	(89,522)	(80,964)		(67,431)
Dividends paid to preferred shareholders	(8,096)	(8,711)		(10,556)
Exercise of stock options	11,762	3,060		2,221
Excess tax benefits from stock-based compensation	3,204	2,338		1,161
Common stock issued	0	0		435
Common stock repurchased	(11,206)	(12,564)		(10,741)
Shares acquired related to employee share-based compensation plans	(11,664)	(5,251)		(2,326)
Common stock warrants repurchased	(163)	(23)		(3)
Net cash (used for) provided by financing activities	1,227,831	457,171		1,434,783
Net (decrease) increase in cash and due from banks	(9,030)	(14,221)		7,993
Cash and due from banks at beginning of period	199,693	213,914		205,921
Cash and due from banks at end of period	190,663	199,693		213,914
Supplemental disclosure of cash flow information:
Interest paid	102,438	95,428		89,942
Income taxes paid	80,143	106,991		102,973
Noncash investing and financing activities:
Transfer of loans and leases to foreclosed properties and repossessed assets	6,769	8,714		5,532
Transfer of loans from portfolio to loans held for sale	39,383	585		0
Deposits assumed in business acquisition	0	1,446,899		0
Preferred stock conversion	$ 0	$ 28,939		$ 0

[1] An additional line item, net decrease (increase) in derivative contract assets net of liabilities, was added to the Consolidated Statements of Cash Flows to detail the net change in derivative balances subject to offsetting. The update removed $6.5 million and $49.2 million in net increases in derivative contract assets net of liabilities from the net (increase) in accrued interest receivable and other assets and net increase in accrued expenses and other liabilities line items for the years ended December 31, 2015 and December 31, 2014 respectively.