Loans - Age Analysis of Loans (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual status, days past due	90 days
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	$ 18,437	$ 29,871
90 Days or More Past Due	3,664	52
Total loans past due and still accruing	22,101	29,923
Nonaccrual	93,452	39,005
Purchased Credit Impaired	34,122	46,174
Current	2,897,943	3,015,567
Loans held for investment	3,047,618	3,130,669	$ 1,982,280
Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	9,084	13,994
90 Days or More Past Due	1,082	45
Total loans past due and still accruing	10,166	14,039
Nonaccrual	60,700	35,703
Current	2,081,193	1,883,815
Loans held for investment	2,152,059	1,933,557	1,809,635
Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	9,353	15,877
90 Days or More Past Due	2,582	7
Total loans past due and still accruing	11,935	15,884
Nonaccrual	32,752	3,302
Purchased Credit Impaired	34,122	46,174
Current	816,750	1,131,752
Loans held for investment	895,559	1,197,112	172,645
Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	1,004,414	1,206,452
Commercial & Industrial [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	746	2,064
90 Days or More Past Due	658	25
Total loans past due and still accruing	1,404	2,089
Nonaccrual	56,452	34,205
Current	765,191	813,754
Loans held for investment	823,047	850,048	802,603
Commercial & Industrial [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	1,963	10,908
90 Days or More Past Due	24
Total loans past due and still accruing	1,987	10,908
Nonaccrual	25,642	420
Purchased Credit Impaired	4,778	13,905
Current	148,960	331,171
Loans held for investment	181,367	356,404	17,734
Owner occupied commercial real estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	387,032	353,889
Owner occupied commercial real estate [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	726	9,158
Total loans past due and still accruing	726	9,158
Nonaccrual	1,454	829
Current	247,647	178,921
Loans held for investment	249,827	188,908	169,296
Owner occupied commercial real estate [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	5,586	741
90 Days or More Past Due	305
Total loans past due and still accruing	5,891	741
Nonaccrual	2,583
Purchased Credit Impaired	5,989	7,149
Current	122,742	157,091
Loans held for investment	137,205	164,981	13,928
Commercial real estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	1,109,642	904,115
Commercial real estate [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due		1,108
Total loans past due and still accruing		1,108
Nonaccrual	2,095
Current	759,693	520,779
Loans held for investment	761,788	521,887	465,989
Commercial real estate [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	989
Total loans past due and still accruing	989
Nonaccrual	2,623	1,590
Purchased Credit Impaired	11,960	12,288
Current	332,282	368,350
Loans held for investment	347,854	382,228	17,639
Construction, land & land development [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	278,323	358,813
Construction, land & land development [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	4,272	181
Total loans past due and still accruing	4,272	181
Nonaccrual		472
Current	176,043	241,958
Loans held for investment	180,315	242,611	247,228
Construction, land & land development [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	460	111
90 Days or More Past Due	2,214
Total loans past due and still accruing	2,674	111
Nonaccrual	358
Purchased Credit Impaired	8,331	8,681
Current	86,645	107,410
Loans held for investment	98,008	116,202	4,978
Residential mortgage [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	256,840	293,483
Residential mortgage [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	3,244	890
90 Days or More Past Due	424
Total loans past due and still accruing	3,668	890
Nonaccrual	580	197
Current	123,829	119,173
Loans held for investment	128,077	120,260	114,733
Residential mortgage [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	322	4,065
90 Days or More Past Due	25	6
Total loans past due and still accruing	347	4,071
Nonaccrual	1,534	1,292
Purchased Credit Impaired	3,064	4,151
Current	123,818	163,709
Loans held for investment	128,763	173,223	116,063
Consumer and other [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	11,367	13,917
Consumer and other [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	96	593
90 Days or More Past Due		20
Total loans past due and still accruing	96	613
Nonaccrual	119
Current	8,790	9,230
Loans held for investment	9,005	9,843	9,786
Consumer and other [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	33	52
90 Days or More Past Due	14	1
Total loans past due and still accruing	47	53
Nonaccrual	12
Current	2,303	4,021
Loans held for investment	$ 2,362	$ 4,074	$ 2,303