Loans (Schedule of Risk Category of Loans) (Details) - USD ($) $ in Thousands		Jun. 30, 2018		Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		$ 2,331,331	[1]	$ 2,154,502	[2]
First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	[1]	115,960
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		7,776		9,117
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		1,783,260		1,660,271
Pass | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		52,771
Pass | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		2,552		2,604
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		38,922		53,226
Special Mention | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0
Special Mention | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		1,597		1,647
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		43,077		41,402
Substandard | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0
Substandard | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		2,759		3,978
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0		0
Doubtful | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0
Doubtful | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0		0
Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		1,865,259		1,754,899
Total | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		52,771
Total | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		6,908		8,229
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		519,749	[1]	488,058	[2]
Commercial and Industrial Loans and Leases | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		783		988
Commercial and Industrial Loans and Leases | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		499,876		462,212
Commercial and Industrial Loans and Leases | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		4,247		7,901
Commercial and Industrial Loans and Leases | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		15,626		17,945
Commercial and Industrial Loans and Leases | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0		0
Commercial and Industrial Loans and Leases | Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		519,749		488,058
Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		988,993	[1]	929,040	[2]
Commercial Real Estate Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		5,174		6,452
Commercial Real Estate Loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		960,045		894,027
Commercial Real Estate Loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		14,248		18,037
Commercial Real Estate Loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		14,700		16,976
Commercial Real Estate Loans | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0		0
Commercial Real Estate Loans | Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		988,993		929,040
Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		356,517	[1]	337,801	[2]
Agricultural Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		951		789
Agricultural Loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		323,339		304,032
Agricultural Loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		20,427		27,288
Agricultural Loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		12,751		6,481
Agricultural Loans | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0		0
Agricultural Loans | Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		$ 356,517		$ 337,801

[1] Total recorded investment in loans includes $9,486 in accrued interest.

[2] Total recorded investment in loans includes $9,483 in accrued interest.