Fair Value Measurements (Carrying Amounts and Estimated Fair Values) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Carrying Amount [Member]
Investment securities:
Available-for-sale	$ 4,755	$ 0
Nonmarketable equity securities	25,572	25,572
Carrying Amount [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	656,135	381,940
Carrying Amount [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	582,054	667,276
Held-to-maturity	229,977	175,339
Loans held-for-sale	17,665	18,818
Interest receivable	14,933	16,308
Liabilities:
Deposits without defined maturities	3,448,886	2,851,883
Interest Payable	1,501	2,147
Short-term borrowings	310,463	303,786
FHLB advances	34,289	43,057
Carrying Amount [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	0	8,000
Net loans	4,083,244	3,742,952
Liabilities:
Time deposits	1,472,557	1,514,974
Fair Value [Member]
Investment securities:
Available-for-sale	4,755	0
Nonmarketable equity securities	25,572	25,572
Fair Value [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	656,135	381,940
Fair Value [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	582,054	667,276
Held-to-maturity	229,922	175,769
Loans held-for-sale	17,665	18,972
Interest receivable	14,933	16,308
Liabilities:
Deposits without defined maturities	3,448,886	2,851,883
Interest Payable	1,501	2,147
Short-term borrowings	310,463	303,786
FHLB advances	34,835	44,307
Fair Value [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	0	8,000
Net loans	4,093,880	3,753,799
Liabilities:
Time deposits	$ 1,489,072	$ 1,538,566