Retirement Plans (Textual) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 18, 2013
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible pay contribution to certain employees	4.00%
Common Stock, Shares Held by Plan	(29,789,825)	(27,498,868)		(2,213,750)
Dividends paid	$ 24,521,000	$ 22,566,000	$ 21,964,000
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum years of vested service for calculation of retirement benefits	30 years
Years of employees highest average salary for calculation of retirement benefits	5 years
Number of years preceding retirement for calculation of retirement benefits	10 years
Maximum years of service for which pension benefits calculation is based upon vested service and average five years of salary	15 years
Maximum total years of age and years of service for which pension benefits calculation is based upon vested service and average five years of salary	65 years
Number of employees covered by the pension plan	200
Employer contributions	15,000,000	12,000,000
Pension plan actual asset allocations	100.00%	100.00%
Projected benefit obligation	105,914,000	115,177,000	100,216,000
Accumulated benefit obligation	99,551,000	108,078,000
Defined Benefit Pension Plan [Member] | Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum	60.00%
Target plan asset allocations range - maximum	70.00%
Pension plan actual asset allocations	70.00%	70.00%
Defined Benefit Pension Plan [Member] | Debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum	30.00%
Target plan asset allocations range - maximum	40.00%
Pension plan actual asset allocations	29.00%	28.00%
Defined Benefit Pension Plan [Member] | Other securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum	0.00%
Target plan asset allocations range - maximum	10.00%
Pension plan actual asset allocations	1.00%	2.00%
Defined Benefit Pension Plan [Member] | Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Common Stock, Shares Held by Plan	(210,663)
Fair value of common stock	6,700,000	5,000,000
Pension plan actual asset allocations	5.20%	5.10%
Supplemental Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	1,700,000	1,600,000
Accumulated benefit obligation	1,500,000	1,400,000
Supplemental Plan expense	200,000	200,000	100,000
Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	219,000	218,000
Projected benefit obligation	3,477,000	3,243,000	3,290,000
Accumulated benefit obligation	3,477,000	3,243,000
Minimum retirement age (years)	50 years
Maximum benefit age of spouse (years)	65 years
Minimum retirement age with twenty-five years of service to be eligible for postretirement benefits (years)	60 years
Minimum years of service for retirees at age sixty to be eligible for postretirement benefits (years)	25 years
Expected health care cost trend rate assumed for 2014	8.50%
Expected ultimate health care cost trend rate in 2020	5.00%
Chemical Financial Corporation [Member] | Defined Benefit Pension Plan [Member] | Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Dividends paid	$ 180,000	$ 180,000