Fair Value Measurements (Schedule of Carrying Amounts and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Investment securities:
Available-for-sale	$ 685,706	$ 748,864	$ 615,975
Held-to-maturity	466,578	315,740	303,961
Carrying Amount [Member]
Investment securities:
Nonmarketable equity securities	36,142	27,369	25,572
Carrying Amount [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	215,034	183,020	140,294
Investment securities:
Available-for-sale	8,294	8,259	0
Carrying Amount [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	677,412	740,605	615,975
Held-to-maturity	469,337	305,913	297,630
Loans Held-for-sale	7,798	9,128	6,329
Interest receivable	21,668	17,492	15,827
Liabilities:
Deposits without defined maturities	5,547,764	4,741,024	3,814,013
Interest payable	1,557	755	735
Short-term borrowings, fair value disclosure	532,291	389,467	305,422
Other Liabilities, Fair Value Disclosure	106,469	0	0
Carrying Amount [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	500	10,500	10,500
Net loans	6,959,802	5,612,547	4,821,011
Liabilities:
Time deposits	1,745,215	1,337,947	1,278,900
Other Liabilities, Fair Value Disclosure	42,021	0	0
Fair Value [Member]
Investment securities:
Nonmarketable equity securities	36,142	27,369	25,572
Fair Value [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	215,034	183,020	140,294
Investment securities:
Available-for-sale	8,294	8,259	0
Fair Value [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	677,412	740,605	615,975
Held-to-maturity	466,278	308,650	297,186
Loans Held-for-sale	7,798	9,128	6,329
Interest receivable	21,668	17,492	15,827
Liabilities:
Deposits without defined maturities	5,547,764	4,741,024	3,814,013
Interest payable	1,557	755	735
Short-term borrowings, fair value disclosure	532,291	389,467	305,422
Other Liabilities, Fair Value Disclosure	106,469	0	0
Fair Value [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	300	7,090	6,775
Net loans	6,969,655	5,623,454	4,826,672
Liabilities:
Time deposits	1,745,215	1,340,015	1,285,992
Other Liabilities, Fair Value Disclosure	$ 42,021	$ 0	$ 0