Loans (Schedule of Risk Category of Loans) (Details) - USD ($) $ in Thousands		Sep. 30, 2018		Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		$ 2,351,277	[1]	$ 2,154,502	[2]
First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	[1]	113,173
Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		7,599		9,117
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		1,770,762		1,660,271
Pass | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		52,105
Pass | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		2,745		2,604
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		64,149		53,226
Special Mention | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0
Special Mention | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		1,802		1,647
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		47,082		41,402
Substandard | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		0
Substandard | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		2,192		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 | Loans 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		1,881,993		1,754,899
Total | First Financial Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		52,105
Total | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		6,739		8,229
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		529,464	[1]	488,058	[2]
Commercial and Industrial Loans and Leases | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		1,189		988
Commercial and Industrial Loans and Leases | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		506,547		462,212
Commercial and Industrial Loans and Leases | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		5,901		7,901
Commercial and Industrial Loans and Leases | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		17,016		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		529,464		488,058
Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		988,575	[1]	929,040	[2]
Commercial Real Estate Loans | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		4,578		6,452
Commercial Real Estate Loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		960,077		894,027
Commercial Real Estate Loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		17,807		18,037
Commercial Real Estate Loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		10,691		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		988,575		929,040
Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		363,954	[1]	337,801	[2]
Agricultural Loans | Loans Acquired With Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		972		789
Agricultural Loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		304,138		304,032
Agricultural Loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		40,441		27,288
Agricultural Loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income		19,375		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		$ 363,954		$ 337,801

[1] Total recorded investment in loans includes $11,104 in accrued interest.

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