Fair Value Measurements (Schedule of Carrying Amounts and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Investment securities:
Available-for-sale	$ 514,015	$ 553,731	$ 680,644
Held-to-maturity	525,593	512,705	380,176
Carrying Amount [Member]
Investment securities:
Nonmarketable equity securities	43,267	36,907	31,249
Carrying Amount [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	291,374	238,789	393,938
Investment securities:
Available-for-sale	5,797	5,765	8,302
Carrying Amount [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	508,218	547,966	672,342
Held-to-maturity	517,800	509,471	370,950
Loans Held-for-sale	9,667	10,327	9,675
Interest receivable	26,010	21,953	19,816
Liabilities:
Deposits without defined maturities	6,043,457	5,809,355	4,988,268
Interest payable	1,632	1,578	779
Short-term borrowings	283,383	397,199	372,236
Other borrowings	256,357	206,394	0
Carrying Amount [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	500	500	10,500
Net loans	7,296,567	7,197,819	5,627,618
Liabilities:
Time deposits	1,606,659	1,647,412	1,332,085
Other borrowings	17,365	35,997	0
Fair Value [Member]
Investment securities:
Nonmarketable equity securities	43,267	36,907	31,249
Fair Value [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	291,374	238,789	393,938
Investment securities:
Available-for-sale	5,797	5,765	8,302
Fair Value [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	508,218	547,966	672,342
Held-to-maturity	525,308	512,405	372,876
Loans Held-for-sale	9,667	10,327	9,675
Interest receivable	26,010	21,953	19,816
Liabilities:
Deposits without defined maturities	6,043,457	5,809,355	4,988,268
Interest payable	1,632	1,578	779
Short-term borrowings	283,383	397,199	372,236
Other borrowings	257,993	206,394	0
Fair Value [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	285	300	7,300
Net loans	7,297,375	7,201,994	5,633,217
Liabilities:
Time deposits	1,609,073	1,647,412	1,335,605
Other borrowings	$ 17,317	$ 35,997	$ 0