Loans (Summary of Loans) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Summary of loans under portfolio
Commercial loan	$ 2,264,820	$ 2,085,325
Consumer loan	1,902,915	1,745,960
Total loans	4,167,735	3,831,285
Commercial [Member]
Summary of loans under portfolio
Commercial loan	1,002,722	895,150
Real estate commercial [Member]
Summary of loans under portfolio
Commercial loan	1,161,861	1,071,999
Real estate construction [Member]
Summary of loans under portfolio
Commercial loan	62,689	73,355
Land development [Member]
Summary of loans under portfolio
Commercial loan	37,548	44,821
Real estate residential [Member]
Summary of loans under portfolio
Consumer loan	883,835	861,716
Consumer installment [Member]
Summary of loans under portfolio
Consumer loan	546,036	484,058
Home equity [Member]
Summary of loans under portfolio
Consumer loan	$ 473,044	$ 400,186