Loans (Summary of Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Summary of loans under portfolio
Commercial loan	$ 4,110,698	$ 3,084,024	$ 2,622,872
Consumer loan	2,924,045	2,604,206	2,275,932
Total loans	7,034,743	5,688,230	4,898,804
Commercial [Member]
Summary of loans under portfolio
Commercial loan	1,754,873	1,354,881	1,212,383
Real estate commercial [Member]
Summary of loans under portfolio
Commercial loan	2,243,513	1,557,648	1,298,365
Real estate construction [Member]
Summary of loans under portfolio
Commercial loan	101,717	152,745	101,168
Land development [Member]
Summary of loans under portfolio
Commercial loan	10,595	18,750	10,956
Real estate residential [Member]
Summary of loans under portfolio
Consumer loan	1,310,167	1,110,390	970,397
Consumer installment [Member]
Summary of loans under portfolio
Consumer loan	887,907	829,570	744,781
Home equity [Member]
Summary of loans under portfolio
Consumer loan	$ 725,971	$ 664,246	$ 560,754