Noncovered Loans Receivable (Credit Quality Indicators) (Details) (Noncovered Loans, USD $)	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Pass	$ 1,985,381,000	$ 1,092,035,000
OAEM	59,368,000	26,710,000
Substandard	80,741,000	49,678,000
Doubtful	324,000	2,413,000
Total	2,125,814,000	1,170,836,000
Potential problem loans receivable	117,250,000	52,814,000
Government guaranteed potential problem loans	2,000,000	1,800,000
Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Pass	1,589,979,000	955,444,000
OAEM	55,076,000	22,034,000
Substandard	58,463,000	37,937,000
Doubtful	324,000	2,413,000
Total	1,703,842,000	1,017,828,000
Real Estate Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Pass	91,381,000	56,914,000
OAEM	3,977,000	4,159,000
Substandard	12,751,000	7,306,000
Doubtful	0	0
Total	108,109,000	68,379,000
Consumer
Financing Receivable, Recorded Investment [Line Items]
Pass	242,836,000	39,432,000
OAEM	0	248,000
Substandard	7,487,000	1,867,000
Doubtful	0	0
Total	250,323,000	41,547,000
Commercial and Industrial | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Pass	509,483,000	304,959,000
OAEM	14,487,000	9,183,000
Substandard	27,049,000	20,849,000
Doubtful	324,000	1,549,000
Total	551,343,000	336,540,000
Owner-occupied Commercial Real Estate | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Pass	496,234,000	269,130,000
OAEM	22,946,000	3,814,000
Substandard	16,562,000	8,365,000
Doubtful	0	0
Total	535,742,000	281,309,000
Non-owner Occupied Commercial Real Estate | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Pass	584,262,000	381,355,000
OAEM	17,643,000	9,037,000
Substandard	14,852,000	8,723,000
Doubtful	0	864,000
Total	616,757,000	399,979,000
One-to-four Family Residential
Financing Receivable, Recorded Investment [Line Items]
Pass	61,185,000	40,245,000
OAEM	315,000	269,000
Substandard	2,040,000	2,568,000
Doubtful	0	0
Total	63,540,000	43,082,000
One-to-four Family Residential | Real Estate Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Pass	34,356,000	11,582,000
OAEM	3,977,000	4,159,000
Substandard	8,416,000	3,983,000
Doubtful	0	0
Total	46,749,000	19,724,000
Five or More Family Residential and Commercial Properties | Real Estate Construction and Land Development
Financing Receivable, Recorded Investment [Line Items]
Pass	57,025,000	45,332,000
OAEM	0	0
Substandard	4,335,000	3,323,000
Doubtful	0	0
Total	$ 61,360,000	$ 48,655,000