Acquisitions and Preliminary Purchase Price Allocation Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2019	Dec. 07, 2018
Business Acquisition [Line Items]
Goodwill	$ 109,567	$ 109,048
Farmers Deposit Bancorp, Inc.
Business Acquisition [Line Items]
Consideration	24,900
Cash and cash equivalents			$ 4,173
Investment securities			46,235
Loans			58,485
Bank owned life insurance			0
Premises and equipment			568
Deferred tax assets			137
Other assets			2,302
Total identifiable assets			111,900
Deposits			92,241
Short-term borrowings			2,025
Long-term debt			0
Other liabilities			651
Total identifiable liabilities			94,917
Net identifiable assets			16,983
Goodwill			4,583
Core deposit intangible			3,334
Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			24,900
Poage Bankshares, Inc.
Business Acquisition [Line Items]
Consideration	83,936
Cash and cash equivalents			34,325
Investment securities			72,321
Loans			304,359
Bank owned life insurance			7,439
Premises and equipment			4,547
Deferred tax assets			2,222
Other assets			8,770
Total identifiable assets			433,983
Deposits			379,285
Short-term borrowings			0
Long-term debt			4,053
Other liabilities			3,032
Total identifiable liabilities			386,370
Net identifiable assets			47,613
Goodwill			28,269
Core deposit intangible			8,054
Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			83,936
Poage and Farmers
Business Acquisition [Line Items]
Consideration	$ 108,836
Cash and cash equivalents			38,498
Investment securities			118,556
Loans			362,844
Bank owned life insurance			7,439
Premises and equipment			5,115
Deferred tax assets			2,359
Other assets			11,072
Total identifiable assets			545,883
Deposits			471,526
Short-term borrowings			2,025
Long-term debt			4,053
Other liabilities			3,683
Total identifiable liabilities			481,287
Net identifiable assets			64,596
Goodwill			32,852
Core deposit intangible			11,388
Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			$ 108,836