Fair Value Measurements - Fair Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial assets:
Fair Value	$ 1,250,777	$ 671,488
Mortgage loans held for sale	219,848	108,316
Obligations of other U.S. Government agencies and corporations
Financial assets:
Fair Value	2,511	3,564
Obligations of states and political subdivisions
Financial assets:
Fair Value	203,269	234,481
Residential mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	613,283	193,950
Residential mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	326,989	176,639
Commercial mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	21,830	31,170
Commercial mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	28,335	5,006
Trust preferred securities
Financial assets:
Fair Value	10,633	9,388
Other debt securities
Financial assets:
Fair Value	43,927	17,290
Quoted Prices In Active Markets for Identical Assets (Level 1)
Financial assets:
Fair Value	0	0
Derivative instruments	0	0
Financial liabilities:
Derivative instruments	0	0
Significant Other Observable Inputs (Level 2)
Financial assets:
Fair Value	1,240,144	662,100
Derivative instruments	6,519	5,977
Financial liabilities:
Derivative instruments	8,388	6,039
Significant Unobservable Inputs (Level 3)
Financial assets:
Fair Value	10,633	9,388
Derivative instruments	0	0
Financial liabilities:
Derivative instruments	0	0
Recurring
Financial assets:
Fair Value	1,250,777	671,488
Derivative instruments	6,519	5,977
Mortgage loans held for sale	219,848	108,316
Total financial assets	1,477,144	785,781
Financial liabilities:
Derivative instruments	8,388	6,039
Total financial liabilities	8,388	6,039
Recurring | Interest rate swap
Financial liabilities:
Derivative instruments	2,046	2,536
Recurring | Interest rate contracts
Financial assets:
Derivative instruments	2,779	3,171
Financial liabilities:
Derivative instruments	2,779	3,171
Recurring | Interest rate lock commitments
Financial assets:
Derivative instruments	3,740	2,756
Financial liabilities:
Derivative instruments	0	4
Recurring | Forward commitments
Financial assets:
Derivative instruments	0	50
Financial liabilities:
Derivative instruments	3,563	328
Recurring | Obligations of other U.S. Government agencies and corporations
Financial assets:
Fair Value	2,511	3,564
Recurring | Obligations of states and political subdivisions
Financial assets:
Fair Value	203,269	234,481
Recurring | Residential mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	613,283	193,950
Recurring | Residential mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	326,989	176,639
Recurring | Commercial mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	21,830	31,170
Recurring | Commercial mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	28,335	5,006
Recurring | Trust preferred securities
Financial assets:
Fair Value	10,633	9,388
Recurring | Other debt securities
Financial assets:
Fair Value	43,927	17,290
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1)
Financial assets:
Fair Value	0	0
Derivative instruments	0	0
Mortgage loans held for sale	0	0
Total financial assets	0	0
Financial liabilities:
Derivative instruments	0	0
Total financial liabilities	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Interest rate swap
Financial liabilities:
Derivative instruments	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Interest rate contracts
Financial assets:
Derivative instruments	0	0
Financial liabilities:
Derivative instruments	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Interest rate lock commitments
Financial assets:
Derivative instruments	0	0
Financial liabilities:
Derivative instruments	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Forward commitments
Financial assets:
Derivative instruments	0	0
Financial liabilities:
Derivative instruments	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Obligations of other U.S. Government agencies and corporations
Financial assets:
Fair Value	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Obligations of states and political subdivisions
Financial assets:
Fair Value	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Residential mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Residential mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Commercial mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Commercial mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Trust preferred securities
Financial assets:
Fair Value	0	0
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Other debt securities
Financial assets:
Fair Value	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Financial assets:
Fair Value	1,240,144	662,100
Derivative instruments	6,519	5,977
Mortgage loans held for sale	219,848	108,316
Total financial assets	1,466,511	776,393
Financial liabilities:
Derivative instruments	8,388	6,039
Total financial liabilities	8,388	6,039
Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swap
Financial liabilities:
Derivative instruments	2,046	2,536
Recurring | Significant Other Observable Inputs (Level 2) | Interest rate contracts
Financial assets:
Derivative instruments	2,779	3,171
Financial liabilities:
Derivative instruments	2,779	3,171
Recurring | Significant Other Observable Inputs (Level 2) | Interest rate lock commitments
Financial assets:
Derivative instruments	3,740	2,756
Financial liabilities:
Derivative instruments	0	4
Recurring | Significant Other Observable Inputs (Level 2) | Forward commitments
Financial assets:
Derivative instruments	0	50
Financial liabilities:
Derivative instruments	3,563	328
Recurring | Significant Other Observable Inputs (Level 2) | Obligations of other U.S. Government agencies and corporations
Financial assets:
Fair Value	2,511	3,564
Recurring | Significant Other Observable Inputs (Level 2) | Obligations of states and political subdivisions
Financial assets:
Fair Value	203,269	234,481
Recurring | Significant Other Observable Inputs (Level 2) | Residential mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	613,283	193,950
Recurring | Significant Other Observable Inputs (Level 2) | Residential mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	326,989	176,639
Recurring | Significant Other Observable Inputs (Level 2) | Commercial mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	21,830	31,170
Recurring | Significant Other Observable Inputs (Level 2) | Commercial mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	28,335	5,006
Recurring | Significant Other Observable Inputs (Level 2) | Trust preferred securities
Financial assets:
Fair Value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Other debt securities
Financial assets:
Fair Value	43,927	17,290
Recurring | Significant Unobservable Inputs (Level 3)
Financial assets:
Fair Value	10,633	9,388
Derivative instruments	0	0
Mortgage loans held for sale	0	0
Total financial assets	10,633	9,388
Financial liabilities:
Derivative instruments	0	0
Total financial liabilities	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swap
Financial liabilities:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Interest rate contracts
Financial assets:
Derivative instruments	0	0
Financial liabilities:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Interest rate lock commitments
Financial assets:
Derivative instruments	0	0
Financial liabilities:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Forward commitments
Financial assets:
Derivative instruments	0	0
Financial liabilities:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Obligations of other U.S. Government agencies and corporations
Financial assets:
Fair Value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Obligations of states and political subdivisions
Financial assets:
Fair Value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Residential mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Residential mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Commercial mortgage backed securities | Government agency mortgage backed securities
Financial assets:
Fair Value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Commercial mortgage backed securities | Government agency collateralized mortgage obligations
Financial assets:
Fair Value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Trust preferred securities
Financial assets:
Fair Value	10,633	9,388
Recurring | Significant Unobservable Inputs (Level 3) | Other debt securities
Financial assets:
Fair Value	$ 0	$ 0