Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Activities
Net income	$ 71,857	$ 52,531
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	8,674	9,377
Depreciation, amortization, and accretion, net	14,479	13,785
Deferred income tax expense	36,014	28,601
Decrease in trading account assets	7,536	296
Originations of mortgage loans held for sale	(156,043)	(138,695)
Proceeds from sales of mortgage loans held for sale	155,245	138,677
Gain on sales of mortgage loans held for sale, net	(3,560)	(3,424)
Increase in other assets	(1,875)	(38,484)
Increase in other liabilities	4,963	17,341
Investment securities gains, net	(7,668)	(67)
Losses and write-downs on other real estate, net	1,790	2,098
Decrease in fair value of private equity investments, net	1,814	391
Loss on early extinguishment of debt, net	0	4,735
Share-based compensation expense	3,360	3,337
Net cash provided by operating activities	136,586	90,499
Investing Activities
Net increase in interest earning deposits with banks	(5,539)	(4,299)
Net decrease (increase) in federal funds sold and securities purchased under resale agreements	8,057	(6,481)
Net increase in interest bearing funds with Federal Reserve Bank	(95,370)	(78,640)
Proceeds from maturities and principal collections of investment securities available for sale	163,386	168,039
Proceeds from sales of investment securities available for sale	282,629	243,609
Purchases of investment securities available for sale	(410,814)	(363,788)
Proceeds from sales of loans	0	4,259
Proceeds from sales of loans	2,773	10,798
Net increase in loans	(419,552)	(344,159)
Purchases of bank-owned life insurance policies	(75,000)	0
Net increase in premises and equipment	(5,497)	(7,830)
Proceeds from sales of other assets held for sale	1,328	0
Net cash used in investing activities	(553,599)	(378,492)
Financing Activities
Net increase in demand and savings deposits	364,517	110,837
Net increase in certificates of deposit	92,955	96,212
Net (decrease) increase in federal funds purchased and securities sold under repurchase agreements	(13,219)	26,954
Repayments on long-term debt	(275,000)	(830,067)
Proceeds from issuance of long-term debt	275,000	1,000,000
Dividends paid to common shareholders	(18,347)	(15,069)
Dividends paid to preferred shareholders	(2,559)	(2,559)
Stock options exercised	1,919	456
Repurchases of common stock	(15,151)	(110,985)
Restricted stock activity	(7,784)	(2,818)
Net cash provided by financing activities	402,331	272,961
Decrease in cash and cash equivalents	(14,682)	(15,032)
Cash and cash equivalents at beginning of period	395,175	367,092
Cash and cash equivalents at end of period	380,493	352,060
Supplemental Cash Flow Information
Income tax payments (refunds), net	210	(656)
Interest paid	31,714	32,141
Non-cash Activities
Premises and equipment transferred to other assets held for sale	0	4,828
Loans foreclosed and transferred to other real estate	2,679	4,328
Loans transferred to other loans held for sale at fair value	8,442	3,834
Securities purchased during the period but settled after period-end	$ 94,560	$ 0