Consolidated Statements of Changes in Shareholders' Equity (parenthetical) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Apr. 12, 2013 Citizens Republic Bancorp	Apr. 12, 2013 FirstMerit Citizens Republic Bancorp
Common Stock, Dividends, Per Share, Cash Paid	$ 0.48	$ 0.48
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	0	0
Stock Issued During Period, Shares, Restricted Stock Award, Gross	575,381	539,132
Treasury Stock, Shares, Acquired	247,288	200,898
Stock Issued During Period, Shares, Treasury Stock Reissued	219,315	174,597
FirstMerit shares of Common Stock issued for Citizens' shares			55,468,283
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				2,408,203