Acquisitions - Schedule of Acquired Loan Data (Details) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Jul. 14, 2017	May 19, 2017
Business Acquisition [Line Items]
Fair Value of Acquired Loans at Acquisition Date, subject to ASC 310-30	$ 7,463
Gross Contractual Amounts Receivable at Acquisition Date, subject to ASC 310-30	20,314
IAB
Business Acquisition [Line Items]
Fair Value of Acquired Loans at Acquisition Date, subject to ASC 310-30	4,838	$ 4,838
Gross Contractual Amounts Receivable at Acquisition Date, subject to ASC 310-30	14,131	14,131
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected, subject to ASC 310-30		8,352
Fair Value of Acquired Loans at Acquisition Date, not subject to ASC 310-30		720,544
Gross Contractual Amounts Receivable at Acquisition Date, not subject to ASC 310-30		864,613
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected, not subject to ASC 310-30		$ 9,786
Arlington Bank
Business Acquisition [Line Items]
Fair Value of Acquired Loans at Acquisition Date, subject to ASC 310-30	2,625		$ 2,625
Gross Contractual Amounts Receivable at Acquisition Date, subject to ASC 310-30	$ 6,183		6,183
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected, subject to ASC 310-30			2,891
Fair Value of Acquired Loans at Acquisition Date, not subject to ASC 310-30			222,055
Gross Contractual Amounts Receivable at Acquisition Date, not subject to ASC 310-30			308,857
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected, not subject to ASC 310-30			$ 2,741