Acquisitions & Divestitures - Summary of Balance Sheet Amounts Relative to Branches Sold (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 08, 2019	Feb. 10, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash, Cash Equivalents, and Federal Funds Sold	$ 167,256				$ 196,552				$ 167,256	$ 196,552
Loans and Leases Receivable, Net Amount	5,271,049				4,306,525				5,271,049	4,306,525
Fixed assets, net	60,013				32,109				60,013	32,109
Goodwill	210,344				117,345				210,344	117,345
Intangible assets, net	26,076				8,553				26,076	8,553
Deposits	5,771,023				4,587,985				5,771,023	4,587,985
Other borrowings	230,886				221,450				230,886	221,450
Investments trust preferred securities	2,900								2,900
Other liabilities	66,747				42,267				66,747	42,267
Total cash paid to JCB shareholders and holders of JCB stock options													$ 29,300
Net income	$ 29,090	$ 29,069	$ 18,424	$ 16,156	$ 23,529	$ 22,516	$ 22,251	$ 20,921	$ 92,739	$ 89,217	$ 48,190
Transaction value including JCB's common stock and stock options													$ 171,000
Adjustments associated with acquisition [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash, Cash Equivalents, and Federal Funds Sold												$ 0
Loans and Leases Receivable, Net Amount												(20,743)
Other Real Estate												(2,059)
Other Investments												0
Fixed assets, net												(300)
Accrued interest receivable												0
Intangible assets, net												23,066
Deferred Tax Assets, State Taxes												(2,386)
Other assets												(1,484)
Total assets acquired												(4,525)
Deposits												36
Accrued interest payable												0
Other liabilities												(827)
Total Liabilities Assumed												(4,592)
Net assets acquired (assumed)												$ 67