Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Activities
Net income per consolidated statements of income	$ 31,248	$ 27,003
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses, net	1,157	3,552
Depreciation and amortization	9,031	8,721
Net amortization of securities	2,612	2,087
Securities losses, net	0	310
Gains on sales of loans, net	(3,550)	(2,591)
Deferred income tax provision	3,900	125
Proceeds from sales of loans held for sale	263,614	238,007
Purchases and originations of loans held for sale	(263,232)	(267,422)
Originations of mortgage servicing rights	(3,440)	(3,072)
Earnings on bank-owned life insurance	(1,227)	(1,226)
Net decrease (increase) in other assets	6,375	(3,511)
Net decrease in other liabilities	(6,693)	(7,185)
Other operating activities, net	90	7,730
Net cash provided by operating activities	39,885	2,528
Investing Activities
Proceeds from maturities, prepayments and calls of securities held to maturity	43,854	72,168
Proceeds from maturities, prepayments and calls of securities available for sale	119,742	99,722
Proceeds from sales of securities available for sale	0	24,693
Purchases of securities held to maturity	(40,556)	(50,031)
Purchases of securities available for sale	(128,430)	(113,654)
Net proceeds from bank-owned life insurance	0	604
Net decrease in federal funds sold and securities purchased under reverse repurchase agreements	0	250
Net (increase) decrease in member bank stock	(144)	8,280
Net increase in loans	(102,573)	(153,989)
Purchases of premises and equipment	(6,319)	(2,814)
Proceeds from sales of premises and equipment	5,050	0
Proceeds from sales of other real estate	6,856	10,328
Purchases of software	(1,065)	(1,565)
Investments in tax credit and other partnerships	(17)	(46)
Net cash used in investing activities	(103,602)	(106,054)
Financing Activities
Net increase in deposits	48,460	45,413
Net (decrease) increase in federal funds purchased and securities sold under repurchase agreements	(15,482)	25,394
Net increase (decrease) in short-term borrowings	99,879	(65)
Payments on long-term FHLB advances	(16)	(30)
Common stock dividends	(15,697)	(15,640)
Shares withheld to pay taxes	(1,543)	(799)
Net cash provided by financing activities	115,601	54,273
Increase (decrease) in cash and cash equivalents	51,884	(49,253)
Cash and cash equivalents at beginning of period	327,706	277,751
Cash and cash equivalents at end of period	$ 379,590	$ 228,498