Loans Held for Investment Internal Risk Grading System (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Credit Risk Grades
Totals	$ 2,118,323	$ 1,628,445	$ 1,466,350
Commercial and industrial
Credit Risk Grades
Totals	454,463	428,207	319,541
Commercial owner occupied
Credit Risk Grades
Totals	382,537	210,995	216,784
SBA
Credit Risk Grades
Totals	50,306	28,404	15,115
Warehouse facilities
Credit Risk Grades
Totals	198,113	113,798	114,032
Commercial non-owner occupied
Credit Risk Grades
Totals	402,786	359,213	360,288
Multi-family
Credit Risk Grades
Totals	400,237	262,965	251,512
One-to-four family
Credit Risk Grades
Totals	84,283	122,795	132,020
Construction
Credit Risk Grades
Totals	124,448	89,682	47,034
Land
Credit Risk Grades
Totals	16,339	9,088	6,271
Other loans
Credit Risk Grades
Totals	4,811	3,298	3,753
Pass
Credit Risk Grades
Totals	2,090,538	1,612,143	1,448,510
Pass | Commercial and industrial
Credit Risk Grades
Totals	449,461	426,379	317,713
Pass | Commercial owner occupied
Credit Risk Grades
Totals	370,185	202,390	206,890
Pass | SBA
Credit Risk Grades
Totals	50,306	28,132	15,115
Pass | Warehouse facilities
Credit Risk Grades
Totals	198,113	113,798	114,032
Pass | Commercial non-owner occupied
Credit Risk Grades
Totals	399,245	355,274	355,878
Pass | Multi-family
Credit Risk Grades
Totals	395,565	261,956	250,494
Pass | One-to-four family
Credit Risk Grades
Totals	83,671	122,146	131,330
Pass | Construction
Credit Risk Grades
Totals	124,448	89,682	47,034
Pass | Land
Credit Risk Grades
Totals	15,143	9,088	6,271
Pass | Other loans
Credit Risk Grades
Totals	4,401	3,298	3,753
Special Mention
Credit Risk Grades
Totals	1,914	773	899
Special Mention | Commercial and industrial
Credit Risk Grades
Totals	267	0	0
Special Mention | Commercial owner occupied
Credit Risk Grades
Totals	678	0	393
Special Mention | SBA
Credit Risk Grades
Totals	0	272	0
Special Mention | Warehouse facilities
Credit Risk Grades
Totals	0	0	0
Special Mention | Commercial non-owner occupied
Credit Risk Grades
Totals	265	0	0
Special Mention | Multi-family
Credit Risk Grades
Totals	704	501	506
Special Mention | One-to-four family
Credit Risk Grades
Totals	0	0	0
Special Mention | Construction
Credit Risk Grades
Totals	0	0	0
Special Mention | Land
Credit Risk Grades
Totals	0	0	0
Special Mention | Other loans
Credit Risk Grades
Totals	0	0	0
Substandard
Credit Risk Grades
Totals	25,871	15,529	16,941
Substandard | Commercial and industrial
Credit Risk Grades
Totals	4,735	1,828	1,828
Substandard | Commercial owner occupied
Credit Risk Grades
Totals	11,674	8,605	9,501
Substandard | SBA
Credit Risk Grades
Totals	0	0	0
Substandard | Warehouse facilities
Credit Risk Grades
Totals	0	0	0
Substandard | Commercial non-owner occupied
Credit Risk Grades
Totals	3,276	3,939	4,410
Substandard | Multi-family
Credit Risk Grades
Totals	3,968	508	512
Substandard | One-to-four family
Credit Risk Grades
Totals	612	649	690
Substandard | Construction
Credit Risk Grades
Totals	0	0	0
Substandard | Land
Credit Risk Grades
Totals	1,196	0	0
Substandard | Other loans
Credit Risk Grades
Totals	$ 410	$ 0	$ 0