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	$ 54,558	$ 57,901	$ 57,404
Adjustments to reconcile net income to net cash provided by operating activities
Provision for loan losses	20,269	20,737	29,809
Depreciation and amortization of premises and equipment	6,276	5,463	5,327
Net accretion on securities	2,408	1,597	1,468
Amortization of intangible assets	3,394	3,046	3,072
Stock based compensation	4,364	3,244	3,782
Bank owned life insurance income	(3,077)	(3,085)	(3,316)
Trading security purchases	(753)	(447)	(184)
Unrealized (gains) losses in trading securities	(103)	193	(214)
Deferred income tax benefit	(10)	(9,478)	(14,955)
Proceeds from sale of loans held for sale	65,160	13,545	83,143
Originations of loans held for sale	(66,252)	(14,167)	(80,469)
Net gains on sales of loans held for sale	(2,469)	(329)	(911)
Net security gains	(599)	(151)	(3,274)
Net gains on sales of other real estate owned	(988)	(2,531)	(517)
Net decrease (increase) in other assets	6,804	(3,579)	6,627
Net increase in other liabilities	(128)	11,806	2,645
Net cash provided by operating activities	88,854	83,765	89,437
Investing activities
Net cash provided by acquisitions	52,871	81,467	0
Securities available for sale:
Proceeds from maturities, calls, and principal paydowns	573,828	541,555	511,394
Proceeds from sales	1,790	2,437	103,253
Purchases	(483,858)	(648,048)	(635,319)
Securities held to maturity:
Proceeds from maturities, calls, and principal paydowns	31,506	47,186	112,399
Purchases	(20,193)	(20,736)	(48,701)
Net (increase) decrease in loans	(277,530)	(172,920)	7,292
Net (increase) decrease in Federal Reserve and FHLB stock	(1,886)	226	8,733
Proceeds from bank owned life insurance	0	758	2,767
Purchases of premises and equipment, net	(6,994)	(9,954)	(6,510)
Proceeds from sales of other real estate owned	3,616	2,531	3,186
Net cash (used in) provided by investing activities	(126,850)	(175,498)	58,494
Financing activities
Net increase in deposits	135,095	87,992	41,306
Net (decrease) increase in short-term borrowings	(18,651)	22,158	3,457
Proceeds from issuance of long-term debt	0	156	0
Repayments of long-term debt	(3,354)	(2,146)	(184,824)
Excess tax benefit from exercise of stock options	8	341	140
Proceeds from the issuance of shares to employee benefit plans and other stock plans	1,387	1,386	1,675
Purchase of treasury stock	(15,490)	(30,502)	(477)
Cash dividends and payment for fractional shares	(26,712)	(27,063)	(27,577)
Net cash provided by (used in) financing activities	72,283	52,322	(166,300)
Net increase (decrease) in cash and cash equivalents	34,287	(39,411)	(18,369)
Cash and cash equivalents at beginning of year	129,381	168,792	187,161
Cash and cash equivalents at end of year	163,668	129,381	168,792
Cash paid during the period for:
Interest	35,344	40,135	54,668
Income taxes, net of refund	25,512	31,258	37,033
Noncash investing activities:
Loans transferred to other real estate owned	2,734	2,927	1,212
Acquisitions:
Fair value of assets acquired	258,467	67,020	0
Fair value of liabilities assumed	285,012	148,487	0
Fair value of debt issued in purchase combination	$ 502	$ 2,460	$ 0