Parent Company Only Financial Statements Financial Position (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets [Abstract]
Investment securities available-for-sale	$ 553,731	$ 748,864
Premises and equipment	106,317	97,496
Goodwill	287,393	180,128
Other assets	246,346	141,467
Total Assets	9,188,797	7,322,143
Liabilities and Equity [Abstract]
Other liabilities	76,466	56,572
Nonrevolving line of credit	25,000
Subordinated Debt	18,544
Shareholders' equity	1,015,974	797,133	$ 696,500	$ 596,341
Total Liabilities and Shareholders' Equity	9,188,797	7,322,143
Chemical Financial Corporation [Member]
Assets [Abstract]
Cash at subsidiary bank	28,884	45,820
Investment in subsidiary bank	1,023,285	745,045
Premises and equipment	3,632	3,601
Goodwill	1,092	1,092
Other assets	13,051	4,654
Total Assets	1,069,944	800,212
Liabilities and Equity [Abstract]
Other liabilities	10,426	3,079
Nonrevolving line of credit	25,000	0
Subordinated Debt	18,544	0
Shareholders' equity	1,015,974	797,133
Total Liabilities and Shareholders' Equity	$ 1,069,944	$ 800,212