CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating activities:
Net income	$ 71,159	$ 68,220
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	9,820	9,801
Amortization of intangible assets	2,642	3,293
Net accretion of premiums and discounts on securities, loans, and borrowings	(2,100)	(2,894)
Stock-based compensation	3,164	3,073
Provision for loan losses	3,120	4,647
Amortization of mortgage servicing rights	307	337
Income from bank-owned life insurance policies	(775)	(760)
Net gain from sale of loans and other assets	(48)	(344)
Net change in loans originated for sale	582	258
Change in other assets and liabilities	(6,219)	5,448
Net cash provided by operating activities	81,652	91,079
Investing activities:
Proceeds from maturities of available-for-sale investment securities	131,709	101,228
Proceeds from maturities of other investment securities	172	12
Purchases of available-for-sale investment securities	(494,436)	(300,120)
Purchases of other securities	(9,947)	(7,761)
Net increase in loans	(84,064)	(114,603)
Cash paid for acquisition, net of cash acquired of $0	0	(924)
Expenditure for intangible asset	(100)	0
Purchases of premises and equipment, net	(9,184)	(7,839)
Net cash used in investing activities	(465,850)	(330,007)
Financing activities:
Net increase in deposits	212,846	71,287
Net change in borrowings, net of payments of $0 and $8	220,100	201,892
Issuance of common stock	8,388	6,115
Purchases of treasury stock	(9,125)	0
Issuances of treasury stock	5,472	0
Cash dividends paid	(36,584)	(33,989)
Tax benefits from share-based payment arrangements	1,541	1,476
Net cash provided by financing activities	402,638	246,781
Change in cash and cash equivalents	18,440	7,853
Cash and cash equivalents at beginning of period	138,396	149,647
Cash and cash equivalents at end of period	156,836	157,500
Supplemental disclosures of cash flow information:
Cash paid for interest	8,249	9,079
Cash paid for income taxes	21,334	19,527
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	12,793	12,255
Transfers from loans to other real estate	2,934	2,111
Purchase of intangible asset	$ 93	$ 0