Allowance for Loan Losses - Summary of Loans Based on Method for Determining Allowance (Detail) - USD ($) $ in Thousands | Mar. 31, 2017 | Dec. 31, 2016 | Mar. 31, 2016 | Dec. 31, 2015 |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | $ 6,918,370 | $ 6,634,894 | | |
Allowance for loan losses | 39,431 | 37,897 | $ 31,995 | $ 29,126 |
New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 6,552,214 | 6,259,406 | | |
Allowance for loan losses | 35,362 | | 26,309 | |
Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 366,156 | 375,488 | | |
Allowance for loan losses | 1,344 | | 2,121 | |
Total real estate loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 5,602,082 | 5,274,680 | | |
Total real estate loans | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 590 | 1,171 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 5,256,937 | 4,920,998 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 5,257,527 | 4,922,169 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 66 | 287 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 23,945 | 21,586 | | |
Total real estate loans | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 6,136 | 7,382 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 163,075 | 165,368 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 209 | 263 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 759 | 765 | | |
Commercial real estate | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 1,871,459 | 1,607,841 | | |
Allowance for loan losses | 9,964 | 10,123 | 9,454 | 8,450 |
Commercial real estate | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 0 | 581 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 1,703,790 | 1,437,846 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 1,703,790 | 1,438,427 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 221 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 8,703 | 7,271 | | |
Allowance for loan losses | 8,703 | | 5,960 | |
Commercial real estate | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 4,328 | 4,720 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 34,024 | 34,066 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 175 | 175 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 169 | 201 | | |
Allowance for loan losses | 344 | | 1,033 | |
Owner-occupied commercial real estate | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 808,527 | 788,291 | | |
Allowance for loan losses | 2,711 | 2,597 | 2,281 | 2,243 |
Owner-occupied commercial real estate | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 0 | 0 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 790,062 | 769,814 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 790,062 | 769,814 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 2,650 | 2,536 | | |
Allowance for loan losses | 2,650 | | 1,877 | |
Owner-occupied commercial real estate | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 0 | 0 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 18,465 | 18,477 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 61 | 61 | | |
Allowance for loan losses | 61 | | 404 | |
1-4 single family residential | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 2,179,750 | 2,111,186 | | |
Allowance for loan losses | 7,913 | 7,379 | 7,309 | 6,425 |
1-4 single family residential | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 524 | 524 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 2,084,442 | 2,012,332 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 2,084,966 | 2,012,856 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 7,639 | 7,049 | | |
Allowance for loan losses | 7,639 | | 6,974 | |
1-4 single family residential | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 778 | 1,612 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 63,891 | 65,242 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 34 | 88 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 209 | 213 | | |
Allowance for loan losses | 243 | | 308 | |
Construction, land and development | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 649,696 | 675,248 | | |
Allowance for loan losses | 4,918 | 4,677 | 3,415 | 3,404 |
Construction, land and development | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 0 | 0 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 627,894 | 651,253 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 627,894 | 651,253 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 4,569 | 4,391 | | |
Allowance for loan losses | 4,569 | | 3,091 | |
Construction, land and development | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 0 | 0 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 5,890 | 6,338 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 44 | 47 | | |
Allowance for loan losses | 44 | | 36 | |
Home equity loans and lines of credit | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 92,650 | 92,114 | | |
Allowance for loan losses | 726 | 648 | 499 | 483 |
Home equity loans and lines of credit | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 66 | 66 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 50,749 | 49,753 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 50,815 | 49,819 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 66 | 66 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 384 | 339 | | |
Allowance for loan losses | 450 | | 220 | |
Home equity loans and lines of credit | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 1,030 | 1,050 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 40,805 | 41,245 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 276 | 243 | | |
Allowance for loan losses | 276 | | 279 | |
Total other loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 1,316,288 | 1,360,214 | | |
Total other loans | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 50 | 0 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 1,294,637 | 1,337,237 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 1,294,687 | 1,337,237 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 50 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 11,301 | 11,670 | | |
Total other loans | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 325 | 325 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 5,488 | 5,824 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 325 | 325 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 51 | 57 | | |
Commercial and industrial | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 1,310,177 | 1,353,831 | | |
Allowance for loan losses | 12,953 | 12,245 | 8,580 | 7,665 |
Commercial and industrial | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 50 | 0 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 1,290,406 | 1,332,869 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 1,290,456 | 1,332,869 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 50 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 11,223 | 11,592 | | |
Allowance for loan losses | 11,273 | | 8,136 | |
Commercial and industrial | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 325 | 325 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 5,162 | 5,490 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 325 | 325 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 45 | 51 | | |
Allowance for loan losses | 370 | | 57 | |
Consumer | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 6,111 | 6,383 | | |
Allowance for loan losses | 246 | 228 | 457 | $ 456 |
Consumer | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 0 | 0 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 4,231 | 4,368 | | |
Loans - Recorded Investment, ASC 310-30 Loans | 4,231 | 4,368 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 78 | 78 | | |
Allowance for loan losses | 78 | | 51 | |
Consumer | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, Individually Evaluated for Impairment | 0 | 0 | | |
Loans - Recorded Investment, Collectively Evaluated for Impairment | 326 | 334 | | |
Allowance for Credit Loss, Individually Evaluated for Impairment | 0 | 0 | | |
Allowance for Credit Loss, Collectively Evaluated for Impairment | 6 | 6 | | |
Allowance for loan losses | 6 | | 4 | |
ASC 310-30 Loans | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 191,132 | 196,589 | | |
Allowance for loan losses | 2,725 | | 3,565 | |
ASC 310-30 Loans | Total real estate loans | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | Total real estate loans | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 175,344 | 179,761 | | |
Allowance for loan losses | 1,253 | 2,523 | | |
ASC 310-30 Loans | Commercial real estate | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | Commercial real estate | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 129,317 | 130,628 | | |
Allowance for loan losses | 917 | 2,255 | 2,461 | |
ASC 310-30 Loans | Owner-occupied commercial real estate | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | Owner-occupied commercial real estate | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | 0 | |
ASC 310-30 Loans | 1-4 single family residential | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | 1-4 single family residential | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 30,115 | 31,476 | | |
Allowance for loan losses | 31 | 29 | 27 | |
ASC 310-30 Loans | Construction, land and development | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | Construction, land and development | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 15,912 | 17,657 | | |
Allowance for loan losses | 305 | 239 | 288 | |
ASC 310-30 Loans | Home equity loans and lines of credit | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | Home equity loans and lines of credit | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | 0 | |
ASC 310-30 Loans | Total other loans | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | Total other loans | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 15,788 | 16,828 | | |
Allowance for loan losses | 1,472 | 421 | | |
ASC 310-30 Loans | Commercial and industrial | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | Commercial and industrial | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 14,234 | 15,147 | | |
Allowance for loan losses | 1,310 | 277 | 387 | |
ASC 310-30 Loans | Consumer | New Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 0 | 0 | | |
Allowance for loan losses | 0 | 0 | | |
ASC 310-30 Loans | Consumer | Acquired Loans | | | | |
Financing Receivable, Recorded Investment, Past Due [Line Items] | | | | |
Loans - Recorded Investment, ASC 310-30 Loans | 1,554 | 1,681 | | |
Allowance for loan losses | $ 162 | $ 144 | $ 402 | |