Loans - Age Analysis of Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 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	$ 37,400	$ 29,871
90 Days or More Past Due	12,147	52
Total loans past due and still accruing	49,547	29,923
Nonaccrual	50,534	39,005
Purchased Credit Impaired	42,652	46,174
Current	3,025,450	3,015,567
Loans held for investment	3,168,183	3,130,669	$ 1,810,842
Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	19,725	13,994
90 Days or More Past Due	624	45
Total loans past due and still accruing	20,349	14,039
Nonaccrual	46,284	35,703
Current	2,008,915	1,883,815
Loans held for investment	2,075,548	1,933,557
Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	17,675	15,877
90 Days or More Past Due	11,523	7
Total loans past due and still accruing	29,198	15,884
Nonaccrual	4,250	3,302
Purchased Credit Impaired	42,652	46,174
Current	1,016,535	1,131,752
Loans held for investment	1,092,635	1,197,112
Commercial & Industrial [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Purchased Credit Impaired	10,791	13,905
Loans held for investment	1,130,710	1,206,452	744,380
Commercial & Industrial [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	9,397	2,064
90 Days or More Past Due	624	25
Total loans past due and still accruing	10,021	2,089
Nonaccrual	44,291	34,205
Current	793,226	813,754
Loans held for investment	847,538	850,048
Commercial & Industrial [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	2,499	10,908
90 Days or More Past Due	9,745
Total loans past due and still accruing	12,244	10,908
Nonaccrual	478	420
Purchased Credit Impaired	10,791	13,905
Current	259,659	331,171
Loans held for investment	283,172	356,404
Owner occupied commercial real estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Purchased Credit Impaired	6,981	7,149
Loans held for investment	367,507	353,889	166,604
Owner occupied commercial real estate [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	3,320	9,158
Total loans past due and still accruing	3,320	9,158
Nonaccrual	792	829
Current	200,938	178,921
Loans held for investment	205,050	188,908
Owner occupied commercial real estate [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	807	741
Total loans past due and still accruing	807	741
Nonaccrual	739
Purchased Credit Impaired	6,981	7,149
Current	153,930	157,091
Loans held for investment	162,457	164,981
Commerical real estate [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Purchased Credit Impaired	12,175	12,288
Loans held for investment	1,020,399	904,115	367,071
Commerical real estate [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	4,006	1,108
Total loans past due and still accruing	4,006	1,108
Current	632,533	520,779
Loans held for investment	636,539	521,887
Commerical real estate [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	6,370
90 Days or More Past Due	1,026
Total loans past due and still accruing	7,396
Nonaccrual	1,555	1,590
Purchased Credit Impaired	12,175	12,288
Current	362,734	368,350
Loans held for investment	383,860	382,228
Construction, land & land development [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Purchased Credit Impaired	8,633	8,681
Loans held for investment	356,207	358,813	273,125
Construction, land & land development [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	1,687	181
Total loans past due and still accruing	1,687	181
Nonaccrual	458	472
Current	250,497	241,958
Loans held for investment	252,642	242,611
Construction, land & land development [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	1,023	111
90 Days or More Past Due	498
Total loans past due and still accruing	1,521	111
Purchased Credit Impaired	8,633	8,681
Current	93,411	107,410
Loans held for investment	103,565	116,202
Residential mortgage [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Purchased Credit Impaired	4,072	4,151
Loans held for investment	280,236	293,483	249,591
Residential mortgage [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	820	890
Total loans past due and still accruing	820	890
Nonaccrual	743	197
Current	122,378	119,173
Loans held for investment	123,941	120,260
Residential mortgage [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	6,937	4,065
90 Days or More Past Due	254	6
Total loans past due and still accruing	7,191	4,071
Nonaccrual	1,478	1,292
Purchased Credit Impaired	4,072	4,151
Current	143,554	163,709
Loans held for investment	156,295	173,223
Consumer and other [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	13,124	13,917	$ 10,071
Consumer and other [Member] | Originated [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	495	593
90 Days or More Past Due		20
Total loans past due and still accruing	495	613
Current	9,343	9,230
Loans held for investment	9,838	9,843
Consumer and other [Member] | Acquired [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	39	52
90 Days or More Past Due		1
Total loans past due and still accruing	39	53
Current	3,247	4,021
Loans held for investment	$ 3,286	$ 4,074