Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities
Net income per consolidated statements of income	$ 36,830	$ 31,248
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses, net	4,111	1,157
Depreciation and amortization	9,376	9,031
Net amortization of securities	2,582	2,612
Gains on sales of loans, net	(4,585)	(3,550)
Deferred income tax provision	3,300	3,900
Proceeds from sales of loans held for sale	241,778	263,614
Purchases and originations of loans held for sale	(223,799)	(263,232)
Originations of mortgage servicing rights	(3,567)	(3,440)
Earnings on bank-owned life insurance	(1,233)	(1,227)
Net change in other assets	8,721	6,375
Net change in other liabilities	(7,379)	(6,693)
Other operating activities, net	(8,362)	90
Net cash provided by operating activities	57,773	39,885
Investing Activities
Proceeds from maturities, prepayments and calls of securities held to maturity	33,102	43,854
Proceeds from maturities, prepayments and calls of securities available for sale	112,280	119,742
Purchases of securities held to maturity	0	(40,556)
Purchases of securities available for sale	(1,390)	(128,430)
Net change in federal funds sold and securities purchased under reverse repurchase agreements	503	0
Net change in member bank stock	16,415	(144)
Net change in loans	100,619	(102,573)
Purchases of premises and equipment	(2,862)	(6,319)
Proceeds from sales of premises and equipment	4	5,050
Proceeds from sales of other real estate	5,310	6,856
Purchases of software	(841)	(1,065)
Investments in tax credit and other partnerships	(17)	(17)
Net cash provided by (used in) investing activities	263,123	(103,602)
Financing Activities
Net change in deposits	398,289	48,460
Net change in federal funds purchased and securities sold under repurchase agreements	(194,994)	(15,482)
Net change in short-term borrowings	(525,124)	99,879
Payments on long-term FHLB advances	(17)	(16)
Common stock dividends	(15,660)	(15,697)
Repurchase and retirement of common stock	(2,502)	0
Shares withheld to pay taxes, long-term incentive plan	(1,380)	(1,543)
Net cash provided by (used in) financing activities	(341,388)	115,601
Net change in cash and cash equivalents	(20,492)	51,884
Cash and cash equivalents at beginning of period	335,768	327,706
Cash and cash equivalents at end of period	$ 315,276	$ 379,590