Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating activities
Net cash provided by operating activities	$ 134,775	$ 104,740
Investing activities
Purchases of securities available for sale	(107,235)	(57,535)
Proceeds from sales of securities available for sale	86,850	86,047
Proceeds from call/maturities of securities available for sale	106,391	121,620
Purchases of securities held to maturity	(99,045)	(89,666)
Proceeds from sales of securities held to maturity		13,033
Proceeds from call/maturities of securities held to maturity	131,483	56,427
Net increase in loans	(270,091)	(5,889)
Purchases of premises and equipment	(13,568)	(3,787)
Proceeds from sales of premises and equipment	108	85
Net cash paid in acquisition		(792)
Net cash received in acquisition		148,443
Net cash (used in) provided by investing activities	(165,107)	267,986
Financing activities
Net increase in noninterest-bearing deposits	22,671	114,236
Net decrease in interest-bearing deposits	(38,880)	(463,039)
Net increase in short-term borrowings	53,474	2,002
Repayment of long-term debt	(85,155)	(70,729)
Cash paid for dividends	(12,832)	(12,803)
Cash received on exercise of stock-based compensation	435	255
Excess tax benefit from stock-based compensation	20
Net cash used in financing activities	(60,267)	(430,078)
Net decrease in cash and cash equivalents	(90,599)	(57,352)
Cash and cash equivalents at beginning of period	209,017	292,669
Cash and cash equivalents at end of period	118,418	235,317
Noncash transactions:
Transfers of loans to other real estate owned	$ 34,217	$ 31,279