Consolidated Statements of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash Flows from Operating Activities:
Net income	$ 132,338,000	$ 97,998,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization, and accretion	40,157,000	37,839,000
Provision for loan and lease losses	29,000,000	51,000,000
Realized loss (gain) on available-for-sale securities, net	51,000	(1,633,000)
Deferred income tax expense	49,433,000	20,485,000
Gain on sale of loans and leases	(11,422,000)	(14,084,000)
Gain on sale of foreclosed assets	(519,000)	(2,681,000)
Loss on sale of fixed assets	428,000	0
Mortgage loans originated for sale	(412,448,000)	(404,902,000)
Proceeds from sale of mortgage loans originated for sale	437,937,000	404,473,000
Increase in cash surrender value of bank-owned life insurance	(6,638,000)	(4,347,000)
Increase in accrued interest receivable	(1,411,000)	(2,511,000)
(Decrease) increase in accrued interest payable	(129,000)	2,514,000
Increase (decrease) in accrued expenses and taxes payable	19,361,000	(17,841,000)
Other, net	(23,249,000)	24,112,000
Net cash provided by operating activities	252,889,000	190,422,000
Cash Flows from Investing Activities:
Net decrease (increase) in restricted short-term investments	32,560,000	(4,686,000)
Activity in available-for-sale securities:
Sales	33,765,000	161,668,000
Maturities, repayments, and calls	512,267,000	501,105,000
Purchases	(522,871,000)	(991,689,000)
Net increase in restricted investment in bank stock	(8,353,000)	(4,277,000)
Net increase in loans and leases	(549,855,000)	(304,561,000)
Purchase of bank-owned life insurance	(6,050,000)	(4,087,000)
Proceeds from bank-owned life insurance	13,539,000	6,366,000
Proceeds from sale of foreclosed assets	16,845,000	29,147,000
Acquisitions	0	(2,487,000)
Additions to premises and equipment, net	(12,360,000)	(6,619,000)
Net cash used in investing activities	(490,513,000)	(620,120,000)
Cash Flows from Financing Activities:
Net increase in deposits	141,639,000	360,535,000
Net (decrease) increase in other short-term borrowings	(129,121,000)	138,723,000
Net increase in short-term FHLB borrowings	412,000,000	100,000,000
Repayment of long-term FHLB borrowings	(16,231,000)	(13,028,000)
Proceeds from issuance of long-term debt	0	150,000,000
Repayment of long-term debt	(55,653,000)	(214,006,000)
Proceeds from issuance of common stock	6,783,000	5,644,000
Purchase of treasury stock	(68,000)	(105,000)
Cash dividends paid	(29,924,000)	(25,284,000)
Net cash provided by financing activities	329,425,000	502,479,000
Net change in cash and cash equivalents	91,801,000	72,781,000
Cash and cash equivalents at January 1	316,592,000	332,145,000
Cash and cash equivalents at September 30	408,393,000	404,926,000
Supplemental Disclosure of Cash Flow Information
Cash paid for interest on deposits and borrowings	77,765,000	92,416,000
Income tax (refunds) payments	(22,440,000)	18,607,000
Supplemental Schedule of Noncash Activities
Real estate acquired in settlement of loans	$ 11,693,000	$ 27,490,000