CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating activities:
Net income	$ 77,068	$ 73,142	$ 63,320
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	11,482	11,374	10,219
Amortization of intangible assets	4,607	4,381	5,957
Net (accretion)/amortization of premiums & discounts on securities, loans and borrowings	(9,379)	(5,373)	2,249
Stock-based compensation	3,668	3,784	3,523
Provision for loan losses	9,108	4,736	7,205
Provision for deferred income taxes	12,032	12,942	9,199
Amortization of mortgage servicing rights	687	868	769
Income from bank-owned life insurance policies	(1,121)	(894)	(458)
(Gain) loss from sale of investment securities and debt extinguishments, net	(291)	61	0
Net loss (gain) on sale of loans and other assets	247	(422)	(1,032)
Net change in loans originated for sale	608	4,047	(309)
Change in other operating assets and liabilities	(292)	(14,268)	(3,554)
Net cash provided by operating activities	108,424	94,378	97,088
Investing activities:
Proceeds from sales of available-for-sale investment securities	5,378	15,330	0
Proceeds from sales of other securities	278	1,032	1,201
Proceeds from maturities of held-to-maturity investment securities	28,340	65,062	76,081
Proceeds from maturities of available-for-sale investment securities	215,223	254,368	157,563
Purchases of held-to-maturity investment securities	(110,925)	(13,292)	(345,187)
Purchases of available-for-sale investment securities	(752,891)	(353,498)	(149,883)
Purchases of other securities	(615)	(2,908)	0
Net (increase) decrease in loans	(239,174)	16,078	68,691
Cash received for acquisitions, net of cash acquired of $5,510, $26,901, and $0, respectively	600,972	4,746	0
Purchases of premises and equipment	(10,846)	(9,613)	(15,716)
Net cash used in investing activities	(264,260)	(22,695)	(207,250)
Financing activities:
Net change in noninterest checking, checking, and savings accounts	240,146	199,812	246,453
Net change in time deposits	(205,314)	(110,166)	(236,893)
Net change in borrowings, net of payments of $220, $25,938 and $26,318	(220)	(19,938)	(26,318)
Issuance of common stock	64,145	5,351	6,433
Cash dividends paid	(40,765)	(34,404)	(30,394)
Tax benefits from share-based payment arrangements	1,524	703	842
Net cash provided by (used in) financing activities	59,516	41,358	(39,877)
Change in cash and cash equivalents	(96,320)	113,041	(150,039)
Cash and cash equivalents at beginning of year	324,878	211,837	361,876
Cash and cash equivalents at end of year	228,558	324,878	211,837
Supplemental disclosures of cash flow information:
Cash paid for interest	51,541	61,564	67,485
Cash paid for income taxes	16,462	20,810	12,630
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	10,699	9,609	7,976
Transfers from loans to other real estate	5,059	5,186	3,839
Acquisitions:
Fair value of assets acquired, excluding acquired cash and intangibles	165,885	815,824	0
Fair value of liabilities assumed	$ 798,031	$ 791,222	$ 0