TRANSACTIONS WITH RELATED PARTIES (Textual) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
First Services L P [Member]
Related Party Transaction [Line Items]
Service Fees Paid to Affiliate	$ 4,700,000	$ 5,000,000	$ 14,500,000	$ 15,000,000
First Services L P [Member] \| Affiliate Services Agreement [Member]
Related Party Transaction [Line Items]
Incurred fees and other revenue from affiliate	54,000	60,000	162,000	180,000
First Services L P [Member] \| Premises [Member]
Related Party Transaction [Line Items]
Proceeds from Rents Received	435,000	435,000	1,300,000	1,304,000
First Brokerage America L L C [Member]
Related Party Transaction [Line Items]
Commissions Received From Unaffliated Third Party Companies	900,000	1,200,000	2,900,000	3,500,000
First Brokerage America L L C [Member] \| Premises [Member]
Related Party Transaction [Line Items]
Proceeds from Rents Received	73,000	113,000	293,000	355,000
Dierbergs Markets Inc [Member]
Related Party Transaction [Line Items]
Operating Leases, Rent Expense, Net	$ 120,000	$ 126,000	$ 373,000	$ 378,000
First Bank [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	53.23%		53.23%
First Capital America, Inc. [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	46.77%		46.77%
Loans to Directors, Executive Officers and/or their Affliates [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	$ 6,700,000		$ 6,700,000		$ 28,800,000

FIRST BANKS, INC 10-Q