Consolidated Statements of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash Flows from Operating Activities:
Net income	$ 114,124,000	$ 132,338,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization, and accretion	47,815,000	40,157,000
Provision for loan and lease losses	18,000,000	29,000,000
Stock compensation expense	3,819,000	2,266,000
Realized (gain) loss on available-for-sale securities, net	(3,285,000)	51,000
Deferred income tax expense	43,281,000	49,433,000
Gain on sale of loans and leases	(9,732,000)	(12,436,000)
Gain on sale of foreclosed assets	(198,000)	(519,000)
(Gain) loss on sale of fixed assets	(168,000)	428,000
Mortgage loans originated for sale	(338,413,000)	(411,434,000)
Proceeds from sale of mortgage loans originated for sale	333,166,000	437,937,000
Increase in cash surrender value of bank-owned life insurance	(4,826,000)	(6,638,000)
Decrease (increase) in accrued interest receivable	1,791,000	(1,411,000)
Increase (decrease) in accrued interest payable	237,000	(129,000)
(Decrease) increase in accrued expenses and taxes payable	(10,343,000)	19,361,000
Other, net	(3,837,000)	(25,515,000)
Net cash provided by operating activities	191,431,000	252,889,000
Cash Flows from Investing Activities:
Net decrease in restricted short-term investments	6,106,000	32,560,000
Activity in available-for-sale securities:
Sales	42,000	33,765,000
Maturities, repayments, and calls	341,842,000	512,267,000
Purchases	(92,662,000)	(522,871,000)
Net decrease (increase) in restricted investment in bank stock	25,113,000	(8,353,000)
Proceeds from sale of loans originated for investment	256,372,000	0
Net increase in loans and leases	(154,325,000)	(549,855,000)
Purchase of bank-owned life insurance	0	(6,050,000)
Proceeds from bank-owned life insurance	4,947,000	13,539,000
Proceeds from sale of foreclosed assets	11,857,000	16,845,000
Additions to premises and equipment, net	(7,667,000)	(12,360,000)
Net cash provided by (used in) investing activities	391,625,000	(490,513,000)
Cash Flows from Financing Activities:
Net increase in deposits	722,242,000	141,639,000
Net decrease in other short-term borrowings	(23,065,000)	(129,121,000)
Net decrease in short-term FHLB borrowings	(600,000,000)	412,000,000
Repayment of long-term FHLB borrowings	(14,606,000)	(16,231,000)
Repayment of long-term debt	(93,530,000)	(55,653,000)
Proceeds from issuance of common stock	4,095,000	6,783,000
Purchases and retirement of common stock	(60,885,000)	0
Purchase of treasury stock	(569,000)	(68,000)
Cash dividends paid	(46,877,000)	(29,924,000)
Net cash (used in) provided by financing activities	(113,195,000)	329,425,000
Net change in cash and cash equivalents	469,861,000	91,801,000
Cash and cash equivalents at January 1	343,324,000	316,592,000
Cash and cash equivalents at September 30	813,185,000	408,393,000
Supplemental Disclosure of Cash Flow Information
Cash paid for interest on deposits and borrowings	70,448,000	77,765,000
Income tax refunds	(720,000)	(22,440,000)
Supplemental Schedule of Noncash Activities
Real estate acquired in settlement of loans	8,850,000	11,693,000
Securities purchased not settled	50,113,000	0
Purchase of common stock not settled	5,470,000	0
Capitalized servicing rights	$ 4,193,000	$ 1,014,000