Parent Company Only Financial Statements Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Other income									$ 1,907	$ 697	$ 861
Interest Expense	$ 5,153	$ 5,234	$ 3,944	$ 3,450	$ 3,563	$ 3,561	$ 3,720	$ 3,866	17,781	14,710	17,414
Operating expenses	57,824	58,265	56,785	51,020	52,616	42,702	42,425	42,182	223,894	179,925	164,948
Federal income tax benefit	(10,200)	(9,600)	(9,100)	(8,100)	(7,050)	(7,450)	(7,100)	(5,900)	(37,000)	(27,500)	(24,300)
Net Income	$ 25,504	$ 24,467	$ 19,024	$ 17,835	$ 15,305	$ 16,767	$ 16,236	$ 13,813	86,830	62,121	56,808
Chemical Financial Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash dividends from subsidiary bank									56,860	64,468	24,488
Other income									144	95	390
Total income									57,004	64,563	24,878
Interest Expense									761	42	0
Operating expenses									7,794	7,200	4,735
Total Expenses									8,555	7,242	4,735
Income (loss) before income taxes and equity in undistributed net income of subsidiary bank									48,449	57,321	20,143
Federal income tax benefit									2,582	2,302	1,556
Equity in undistributed net income of subsidiary bank									35,799	2,498	35,109
Net Income									$ 86,830	$ 62,121	$ 56,808