Loans and Allowance for Loan Losses - Credit Quality Indicators by Portfolio Class (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	$ 3,158,911	$ 3,078,076
Purchased credit impaired loans	85,752	88,835
Total loans	3,244,663	3,166,911
Pass
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	3,013,068	2,940,174
Total loans	3,013,068	2,940,174
Watch
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	123,747	114,401
Purchased credit impaired loans	55,013	56,848
Total loans	178,760	171,249
Substandard
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	22,096	23,501
Purchased credit impaired loans	30,739	31,987
Total loans	52,835	55,488
Commercial and Industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	763,164	712,931
Purchased credit impaired loans	1,951	2,144
Total loans	765,115	715,075
Commercial and Industrial | Pass
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	704,689	657,595
Commercial and Industrial | Watch
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	54,124	50,946
Purchased credit impaired loans	1,351	1,499
Commercial and Industrial | Substandard
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	4,351	4,390
Purchased credit impaired loans	600	645
Construction
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	459,070	440,598
Purchased credit impaired loans	7,425	7,728
Total loans	466,495	448,326
Construction | Pass
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	441,718	431,242
Construction | Watch
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	15,468	7,388
Purchased credit impaired loans	3,422	3,324
Construction | Substandard
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	1,884	1,968
Purchased credit impaired loans	4,003	4,404
Residential Real Estate | 1-to-4 Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	468,821	457,491
Purchased credit impaired loans	22,904	23,498
Total loans	491,725	480,989
Residential Real Estate | Residential Line of Credit
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	197,740	194,986
Total loans	197,740	194,986
Residential Real Estate | Multi-Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	63,277	62,354
Purchased credit impaired loans	18	20
Total loans	63,295	62,374
Residential Real Estate | Pass | 1-to-4 Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	452,858	440,202
Residential Real Estate | Pass | Residential Line of Credit
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	194,887	192,427
Residential Real Estate | Pass | Multi-Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	62,175	61,234
Residential Real Estate | Watch | 1-to-4 Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	9,027	9,522
Purchased credit impaired loans	19,454	20,284
Residential Real Estate | Watch | Residential Line of Credit
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	1,677	1,184
Residential Real Estate | Watch | Multi-Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	138	142
Residential Real Estate | Substandard | 1-to-4 Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	6,936	7,767
Purchased credit impaired loans	3,450	3,214
Residential Real Estate | Substandard | Residential Line of Credit
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	1,176	1,375
Residential Real Estate | Substandard | Multi-Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	964	978
Purchased credit impaired loans	18	20
Commercial Real Estate | Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	487,561	483,910
Purchased credit impaired loans	11,770	11,962
Total loans	499,331	495,872
Commercial Real Estate | Non-Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	544,064	533,424
Purchased credit impaired loans	18,064	18,164
Total loans	562,128	551,588
Commercial Real Estate | Pass | Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	457,347	451,140
Commercial Real Estate | Pass | Non-Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	527,134	517,253
Commercial Real Estate | Watch | Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	25,962	28,308
Purchased credit impaired loans	4,565	4,631
Commercial Real Estate | Watch | Non-Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	14,972	14,199
Purchased credit impaired loans	7,517	7,359
Commercial Real Estate | Substandard | Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	4,252	4,462
Purchased credit impaired loans	7,205	7,331
Commercial Real Estate | Substandard | Non-Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	1,958	1,972
Purchased credit impaired loans	10,547	10,805
Consumer and Other
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	175,214	192,382
Purchased credit impaired loans	23,620	25,319
Total loans	198,834	217,701
Consumer and Other | Pass
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	172,260	189,081
Consumer and Other | Watch
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	2,379	2,712
Purchased credit impaired loans	18,704	19,751
Consumer and Other | Substandard
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	575	589
Purchased credit impaired loans	$ 4,916	$ 5,568