Fair Value Measurements (Schedule of Carrying Amounts and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Investment securities:
Held-to-maturity	$ 575,144	$ 512,705
Carrying Amount [Member]
Investment securities:
Nonmarketable equity securities	77,396	36,907
Carrying Amount [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	556,567	238,789
Carrying Amount [Member] | Level 2 [Member]
Investment securities:
Held-to-maturity	563,221	509,471
Interest receivable	43,131	21,953
Liabilities:
Deposits without defined maturities	9,924,502	5,809,355
Time deposits	3,348,360	1,647,412
Interest payable	5,097	1,578
Short-term borrowings	726,789	397,199
Long-term borrowings	676,612	242,391
Carrying Amount [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	500	500
Net loans	12,642,014	7,197,819
Fair Value [Member]
Investment securities:
Nonmarketable equity securities	77,396	36,907
Fair Value [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	556,567	238,789
Fair Value [Member] | Level 2 [Member]
Investment securities:
Held-to-maturity	574,844	512,405
Interest receivable	43,131	21,953
Liabilities:
Deposits without defined maturities	9,924,502	5,809,355
Time deposits	3,348,942	1,647,412
Interest payable	5,097	1,578
Short-term borrowings	726,789	397,199
Long-term borrowings	676,750	242,391
Fair Value [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	300	300
Net loans	$ 12,650,332	$ 7,201,994