CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating activities:
Net income	$ 73,142	$ 63,320	$ 41,445
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	11,374	10,219	10,299
Amortization of intangible assets	4,382	5,957	8,170
Goodwill Impairment	0	0	3,079
Net (accretion)/amortization of premiums & discounts on securities, loans and borrowings	(1,934)	2,249	2,141
Stock-based compensation	3,784	3,523	3,100
Provision for loan losses	4,736	7,205	9,790
Provision for deferred income taxes	12,942	9,199	3,434
Amortization of mortgage servicing rights	868	769	731
Income from bank-owned life insurance policies	(894)	(458)	(476)
Loss (Gain) from sale of investment securities and debt extinguishments, net	61	0	(7)
Net gain on sale of loans and other assets	(422)	(1,032)	(1,098)
Net change in loans originated for sale	4,047	(309)	1,092
Change in other operating assets and liabilities	(14,269)	(3,554)	(37,566)
Net cash provided by operating activities	97,817	97,088	44,134
Investing activities:
Proceeds from sales of available-for-sale investment securities	15,330	0	27
Proceeds from sales of other securities	1,032	1,201	0
Proceeds from maturities of held-to-maturity investment securities	65,062	76,081	108,927
Proceeds from maturities of available-for-sale investment securities	254,368	157,563	253,629
Purchases of held-to-maturity investment securities	(13,292)	(345,187)	(369,374)
Purchases of available-for-sale investment securities	(353,498)	(149,883)	(94,339)
Purchases of other securities	(2,908)	0	(390)
Net decrease in loans	12,639	68,691	29,200
Cash received /(paid) for acquisitions, net of cash acquired	4,746	0	(358)
Purchases of premises and equipment	(9,613)	(15,716)	(13,894)
Net cash (used in) investing activities	(26,134)	(207,250)	(86,572)
Financing activities:
Net change in noninterest checking, checking, and savings accounts	199,812	246,453	491,821
Net change in time deposits	(110,166)	(236,893)	(268,147)
Net change in borrowings, net of payments	(19,938)	(26,318)	(5,779)
Issuance of common stock	5,351	6,433	1,241
Cash dividends paid	(34,404)	(30,394)	(28,788)
Tax benefits from share-based payment arrangements	703	842	213
Net cash provided by/(used in) financing activities	41,358	(39,877)	190,561
Change in cash and cash equivalents	113,041	(150,039)	148,123
Cash and cash equivalents at beginning of year	211,837	361,876	213,753
Cash and cash equivalents at end of year	324,878	211,837	361,876
Supplemental disclosures of cash flow information:
Cash paid for interest	61,564	67,485	85,011
Cash paid for income taxes	20,810	12,630	5,434
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	9,609	7,976	7,211
Transfers from loans to other real estate	5,186	3,839	2,373
Acquisitions:
Fair value of assets acquired, excluding acquired cash and intangibles	815,824	0	63
Fair value of liabilities assumed	$ 791,222	$ 0	$ 0