Loans and Allowance for Loan Losses - Credit Quality Indicators by Portfolio Class (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	$ 3,464,880	$ 3,078,076
Purchased credit impaired loans	73,651	88,835
Total loans	3,538,531	3,166,911
Pass
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	3,325,579	2,940,174
Total loans	3,325,579	2,940,174
Watch
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	101,401	114,401
Purchased credit impaired loans	51,205	56,848
Total loans	152,606	171,249
Substandard
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	37,900	23,501
Purchased credit impaired loans	22,446	31,987
Total loans	60,346	55,488
Commercial and Industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	838,836	712,931
Purchased credit impaired loans	1,603	2,144
Total loans	840,439	715,075
Commercial and Industrial | Pass
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	781,698	657,595
Commercial and Industrial | Watch
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	50,230	50,946
Purchased credit impaired loans	1,068	1,499
Commercial and Industrial | Substandard
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	6,908	4,390
Purchased credit impaired loans	535	645
Construction
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	484,348	440,598
Purchased credit impaired loans	6,823	7,728
Total loans	491,171	448,326
Construction | Pass
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	479,035	431,242
Construction | Watch
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	3,926	7,388
Purchased credit impaired loans	3,276	3,324
Construction | Substandard
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	1,387	1,968
Purchased credit impaired loans	3,547	4,404
Residential Real Estate | 1-to-4 Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	533,631	457,491
Purchased credit impaired loans	20,089	23,498
Total loans	553,720	480,989
Residential Real Estate | Residential Line of Credit
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	214,741	194,986
Total loans	214,741	194,986
Residential Real Estate | Multi-Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	86,264	62,354
Purchased credit impaired loans		20
Total loans	86,264	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	517,598	440,202
Residential Real Estate | Pass | Residential Line of Credit
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	211,114	192,427
Residential Real Estate | Pass | Multi-Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	86,000	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	9,119	9,522
Purchased credit impaired loans	15,666	20,284
Residential Real Estate | Watch | Residential Line of Credit
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	1,328	1,184
Residential Real Estate | Watch | Multi-Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	78	142
Residential Real Estate | Substandard | 1-to-4 Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	6,914	7,767
Purchased credit impaired loans	4,423	3,214
Residential Real Estate | Substandard | Residential Line of Credit
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	2,299	1,375
Residential Real Estate | Substandard | Multi-Family Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	186	978
Purchased credit impaired loans		20
Commercial Real Estate | Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	496,666	483,910
Purchased credit impaired loans	7,483	11,962
Total loans	504,149	495,872
Commercial Real Estate | Non-Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	611,773	533,424
Purchased credit impaired loans	16,563	18,164
Total loans	628,336	551,588
Commercial Real Estate | Pass | Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	465,223	451,140
Commercial Real Estate | Pass | Non-Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	593,771	517,253
Commercial Real Estate | Watch | Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	17,022	28,308
Purchased credit impaired loans	4,311	4,631
Commercial Real Estate | Watch | Non-Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	16,720	14,199
Purchased credit impaired loans	8,433	7,359
Commercial Real Estate | Substandard | Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	14,421	4,462
Purchased credit impaired loans	3,172	7,331
Commercial Real Estate | Substandard | Non-Owner Occupied
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	1,282	1,972
Purchased credit impaired loans	8,130	10,805
Consumer and Other
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	198,621	192,382
Purchased credit impaired loans	21,090	25,319
Total loans	219,711	217,701
Consumer and Other | Pass
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	191,140	189,081
Consumer and Other | Watch
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	2,978	2,712
Purchased credit impaired loans	18,451	19,751
Consumer and Other | Substandard
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, excluding purchased credit impaired loans	4,503	589
Purchased credit impaired loans	$ 2,639	$ 5,568