Fair Value Measurements (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Estimated fair values of company's financial instruments
Cash and cash equivalents	$ 1,945,148	$ 1,707,733	$ 1,204,079	$ 1,036,510
Securities held for investment	16,416	22,477
Total loans (net of unearned interest)	3,242,427	3,013,498
Allowance for loan losses	(38,725)	(37,656)
Loans, net	3,203,702	2,975,842
Deposits	5,440,830	5,037,735
Short-term borrowings	4,571	8,274
Long-term borrowings	9,178	18,476
Junior subordinated debentures	26,804	36,083
Carrying Amount [Member]
Estimated fair values of company's financial instruments
Cash and cash equivalents	1,945,848	1,708,133
Securities held for investment	16,416	22,477
Total loans (net of unearned interest)	3,242,427	3,013,498
Allowance for loan losses	(38,725)	(37,656)
Loans, net	3,203,702	2,975,842
Deposits	5,440,830	5,037,735
Short-term borrowings	4,571	8,274
Long-term borrowings	9,178	18,476
Junior subordinated debentures	26,804	36,083
Fair Value [Member]
Estimated fair values of company's financial instruments
Cash and cash equivalents	1,945,848	1,708,133
Securities held for investment	16,689	22,958
Loans, net	3,264,948	3,022,619
Deposits	5,466,958	5,052,470
Short-term borrowings	4,571	8,274
Long-term borrowings	9,224	18,578
Junior subordinated debentures	28,144	39,300
Loan commitments	1,498	1,257
Letters of credit	$ 440	$ 419

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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