Segment Reporting (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) segment	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			2
Segment Reporting Information [Line Items]
Net interest income	$ 59,724	$ 51,491	$ 171,298	$ 150,902
Provision for loan losses	3,181	2,553	10,526	11,635
Total noninterest income	24,980	20,606	86,304	60,991
Total noninterest expense	61,996	54,655	185,092	161,852
INCOME BEFORE INCOME TAXES	19,527	14,889	61,984	38,406
Average Loans, for the period	4,654,179	3,812,218	4,457,715	3,692,718
Segment Assets, at period end	6,805,884	5,934,809	6,805,884	5,934,809	$ 6,051,812
Operating Segments | Community and Other Banking
Segment Reporting Information [Line Items]
Net interest income	58,123	50,790	167,000	148,930
Provision for loan losses	3,181	2,553	10,526	11,635
Total noninterest income	16,015	11,568	48,679	35,085
Total noninterest expense	49,168	43,228	145,614	129,108
INCOME BEFORE INCOME TAXES	21,789	16,577	59,539	43,272
Average Loans, for the period	4,563,221	3,736,917	4,365,908	3,629,822
Segment Assets, at period end	6,676,526	5,817,427	6,676,526	5,817,427
Operating Segments | Retail Mortgage Banking
Segment Reporting Information [Line Items]
Net interest income	1,601	701	4,298	1,972
Provision for loan losses	0	0	0	0
Total noninterest income	8,965	9,038	37,625	25,906
Total noninterest expense	12,828	11,427	39,478	32,744
INCOME BEFORE INCOME TAXES	(2,262)	(1,688)	2,445	(4,866)
Average Loans, for the period	90,958	75,301	91,807	62,896
Segment Assets, at period end	$ 129,358	$ 117,382	$ 129,358	$ 117,382