Loans (Summary of Loans) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Summary of loans under portfolio
Commercial loan	$ 2,698,808	$ 2,518,826	$ 2,445,787
Consumer loan	2,342,112	2,128,795	2,076,884
Total loans	5,040,920	4,647,621	4,522,671
Commercial [Member]
Summary of loans under portfolio
Commercial loan	1,239,946	1,176,307	1,128,122
Real estate commercial [Member]
Summary of loans under portfolio
Commercial loan	1,322,646	1,232,658	1,215,631
Real estate construction [Member]
Summary of loans under portfolio
Commercial loan	125,782	89,795	78,361
Land development [Member]
Summary of loans under portfolio
Commercial loan	10,434	20,066	23,673
Real estate residential [Member]
Summary of loans under portfolio
Consumer loan	984,049	960,423	942,777
Consumer installment [Member]
Summary of loans under portfolio
Consumer loan	783,443	644,769	622,040
Home equity [Member]
Summary of loans under portfolio
Consumer loan	$ 574,620	$ 523,603	$ 512,067