Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating Activities
Net income	$ 112,989	$ 109,756
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	16,070	11,034
Depreciation, amortization, and accretion, net	28,506	28,169
Deferred income tax expense	61,283	58,302
Decrease in trading account assets	4,096	1,891
Originations of mortgage loans held for sale	(320,304)	(454,708)
Proceeds from sales of mortgage loans held for sale	299,186	426,430
Gain on sales of mortgage loans held for sale, net	(6,946)	(8,988)
Increase in other assets	(32,874)	(36,398)
Increase (decrease) in other liabilities	13,162	(34,914)
Investment securities gains, net	(67)	(2,710)
Losses and write-downs on other real estate, net	6,089	11,066
Losses and write-downs on other assets held for sale, net	7,902	0
Loss on early extinguishment of debt	4,735	0
Share-based compensation expense	6,849	6,271
Net cash provided by operating activities	200,676	115,201
Investing Activities
Net increase in interest earning deposits with banks	(7,154)	(6,884)
Net (increase) decrease in federal funds sold and securities purchased under resale agreements	(7,866)	623
Net increase in interest bearing funds with Federal Reserve Bank	(74,519)	(567,843)
Proceeds from maturities and principal collections of investment securities available for sale	443,128	314,239
Proceeds from sales of investment securities available for sale	243,609	82,156
Purchases of investment securities available for sale	(623,046)	(686,074)
Proceeds from sales of loans and principal repayments on other loans held for sale	7,739	21,866
Proceeds from sales of loans and principal repayments on other loans held for sale	16,282	19,348
Net increase in loans	(660,778)	(445,124)
Net increase in premises and equipment	(16,769)	(8,805)
Proceeds from sales of other assets held for sale	296	351
Net cash used in investing activities	(679,078)	(1,276,147)
Financing Activities
Net increase in demand and savings deposits	595,342	1,039,670
Net increase in certificates of deposit	87,466	77,813
Net increase in federal funds purchased and securities sold under repurchase agreements	70,154	61,369
Repayments on long-term debt	(1,455,067)	(425,078)
Proceeds from issuance of long-term debt	1,400,000	425,000
Dividends paid to common shareholders	(30,015)	(26,664)
Dividends paid to preferred shareholders	(5,119)	(5,119)
Stock options exercised	2,035	3,271
Repurchases of common stock	(171,547)	(109,570)
Restricted stock activity	(4,605)	(4,403)
Net cash provided by financing activities	488,644	1,036,289
Increase (decrease) in cash and cash equivalents	10,242	(124,657)
Cash and cash equivalents at beginning of period	367,092	485,489
Cash and cash equivalents at end of period	377,334	360,832
Supplemental Cash Flow Information
Income tax payments, net	5,849	8,751
Interest paid	64,424	55,747
Non-cash Activities
Premises and equipment transferred to other assets held for sale	18,677	939
Loans foreclosed and transferred to other real estate	8,631	11,391
Loans transferred to other loans held for sale at fair value	7,314	19,459
Securities purchased during the period but settled after period-end	$ 0	$ 47,159