Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	May. 13, 2015	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Shareholders Equity Narrative [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		500,000	800,000
Payments for Repurchase of Warrants	$ 12.2
Adjustments to Additional Paid in Capital, Other		$ (9.2)
5.875% Non-Cumulative Perpetual Preferred stock, Series A, authorized 115,000 shares		7,000,000
Non-cumulative Perpetual Preferred Stock, Series A, Shares Authorized		115,000	115,000	115,000
Non-Cumulative Perpetual Preferred stock, Series A, Shares Outstanding		100,000	100,000	100,000
Citizens Republic Bancorp
Shareholders Equity Narrative [Line Items]
Interest rate of Non-Cumulative Perpetual Preferred Stock, Series A		5.875%
Citizens Republic Bancorp | Citizens Republic Bancorp
Shareholders Equity Narrative [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 17.50
FirstMerit | Citizens Republic Bancorp
Shareholders Equity Narrative [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	2,571,998.380