Loans - Age Analysis of Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
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	$ 17,436	$ 20,461
90 Days or More Past Due	5,500	1,169
Total loans past due and still accruing	22,936	21,630
Nonaccrual	69,614	76,806
Purchased Credit Impaired	22,476	25,188
Current	2,897,249	2,974,596
Loans held for investment	3,012,275	3,098,220	$ 3,168,183
Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	8,774	11,373
90 Days or More Past Due	3,842	1,169
Total loans past due and still accruing	12,616	12,542
Nonaccrual	45,017	39,763
Current	2,224,578	2,249,623
Loans held for investment	2,282,211	2,301,928	2,075,548
Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	8,662	9,088
90 Days or More Past Due	1,658
Total loans past due and still accruing	10,320	9,088
Nonaccrual	24,597	37,043
Purchased Credit Impaired	22,476	25,188
Current	672,671	724,973
Loans held for investment	730,064	796,292	1,092,635
Commercial & Industrial
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	1,012,982	1,053,925
Commercial & Industrial | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	2,193	1,515
90 Days or More Past Due	1,506	1,106
Total loans past due and still accruing	3,699	2,621
Nonaccrual	40,263	36,331
Current	845,886	865,379
Loans held for investment	889,848	904,331	847,538
Commercial & Industrial | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	5,401	2,854
90 Days or More Past Due	1,172
Total loans past due and still accruing	6,573	2,854
Nonaccrual	11,094	23,424
Purchased Credit Impaired	3,805	4,506
Current	101,662	118,810
Loans held for investment	123,134	149,594	283,172
Owner occupied commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	415,595	394,210
Owner occupied commercial real estate | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	534	1,941
90 Days or More Past Due	915
Total loans past due and still accruing	1,449	1,941
Current	290,964	262,935
Loans held for investment	292,413	264,876	205,050
Owner occupied commercial real estate | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	470	223
Total loans past due and still accruing	470	223
Nonaccrual	8,743	8,942
Purchased Credit Impaired	5,246	5,339
Current	108,723	114,830
Loans held for investment	123,182	129,334	162,457
Commercial real estate
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	1,129,031	1,143,751
Commercial real estate | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	1,612	1,612
90 Days or More Past Due	396
Total loans past due and still accruing	2,008	1,612
Nonaccrual	2,021	2,059
Current	804,997	812,358
Loans held for investment	809,026	816,029	636,539
Commercial real estate | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	59	2,529
90 Days or More Past Due	175
Total loans past due and still accruing	234	2,529
Nonaccrual	1,912	2,002
Purchased Credit Impaired	10,699	10,807
Current	307,160	312,384
Loans held for investment	320,005	327,722	383,860
Construction, land & land development
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	201,946	249,704
Construction, land & land development | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	1,575	4,375
90 Days or More Past Due	1,025
Total loans past due and still accruing	2,600	4,375
Current	148,514	175,624
Loans held for investment	151,114	179,999	252,642
Construction, land & land development | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	884	488
90 Days or More Past Due	311
Total loans past due and still accruing	1,195	488
Nonaccrual	1,336	978
Purchased Credit Impaired	18	1,819
Current	48,283	66,420
Loans held for investment	50,832	69,705	103,565
Residential mortgage
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	241,839	245,191
Residential mortgage | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	2,816	1,791
90 Days or More Past Due		63
Total loans past due and still accruing	2,816	1,854
Nonaccrual	2,614	1,254
Current	125,369	124,337
Loans held for investment	130,799	127,445	123,941
Residential mortgage | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	1,846	2,768
Total loans past due and still accruing	1,846	2,768
Nonaccrual	1,296	1,692
Purchased Credit Impaired	2,708	2,717
Current	105,190	110,569
Loans held for investment	111,040	117,746	156,295
Consumer and other
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans held for investment	10,882	11,439
Consumer and other | Originated
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	44	139
Total loans past due and still accruing	44	139
Nonaccrual	119	119
Current	8,848	8,990
Loans held for investment	9,011	9,248	9,838
Consumer and other | Acquired
Financing Receivable, Recorded Investment, Aging [Abstract]
30-89 Past Due	2	226
Total loans past due and still accruing	2	226
Nonaccrual	216	5
Current	1,653	1,960
Loans held for investment	$ 1,871	$ 2,191	$ 3,286