Employee Retirement Plans (Defined Contribution Plans) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Employee stock ownership plan contribution	$ 0	$ 0
Quad/Graphics Diversified Plan
Defined Contribution Plan Disclosure [Line Items]
Total assets	2,200,000,000
Defined contribution plan, cost recognized	$ 11,700,000	$ 15,400,000