Contingencies Contingencies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 29, 2018
Fujitsu [Member]
Commitments and Contingencies Disclosure [Abstract]
Loss Contingency, Management's Assessment and Process	As previously disclosed, we continue to be in dispute with Fujitsu Services Limited ("Fujitsu") regarding Fujitsu's obligation to pay amounts to us due upon the termination of a subcontract, including client receivables, in connection with Fujitsu's contract as the prime contractor in the National Health Service ("NHS") initiative to automate clinical processes and digitize medical records in the Southern region of England. The NHS terminated its contract with Fujitsu, which gave rise to the termination of our subcontract with Fujitsu. We filed a request for arbitration with the London Court of International Arbitration on April 22, 2019 seeking damages. On December 30, 2019, Fujitsu filed its Defense and Counterclaim (the "Counterclaim") in response. In its Counterclaim, Fujitsu defends against our claim in full and argues that we are liable to Fujitsu for: (i) £306 million in damages based on our alleged fraudulent misrepresentations inducing Fujitsu to enter into the subcontract; or (ii) alternatively, £173.8 million in damages based on our alleged breaches of the subcontract.
Loss Contingencies [Line Items]
Loss Contingency, Management's Assessment and Process	As previously disclosed, we continue to be in dispute with Fujitsu Services Limited ("Fujitsu") regarding Fujitsu's obligation to pay amounts to us due upon the termination of a subcontract, including client receivables, in connection with Fujitsu's contract as the prime contractor in the National Health Service ("NHS") initiative to automate clinical processes and digitize medical records in the Southern region of England. The NHS terminated its contract with Fujitsu, which gave rise to the termination of our subcontract with Fujitsu. We filed a request for arbitration with the London Court of International Arbitration on April 22, 2019 seeking damages. On December 30, 2019, Fujitsu filed its Defense and Counterclaim (the "Counterclaim") in response. In its Counterclaim, Fujitsu defends against our claim in full and argues that we are liable to Fujitsu for: (i) £306 million in damages based on our alleged fraudulent misrepresentations inducing Fujitsu to enter into the subcontract; or (ii) alternatively, £173.8 million in damages based on our alleged breaches of the subcontract.
Loss Contingency Accrual, Provision		$ 45
NextGen [Member]
Commitments and Contingencies Disclosure [Abstract]
Loss Contingency, Management's Assessment and Process	Cerner Health Services, Inc. ("Cerner HS"), a wholly owned subsidiary of Cerner Corporation, filed a lawsuit in the Chester County, Pennsylvania, Court of Common Pleas against NextGen Healthcare Information Systems, LLC ("NextGen") relating to a dispute arising out of a supplier relationship initially established between Siemens Health Services, Inc. and NextGen prior to the acquisition of the assets of Siemens Health Services, Inc. by Cerner HS in 2015. In September 2017, the court issued a preliminary injunction to prevent NextGen from refusing to honor certain contractual obligations to support Cerner HS's clients who use NextGen ambulatory EHR solutions. In September 2018, NextGen filed a counterclaim alleging breach of contract and tortious interference but did not specify its damages. In August 2019, NextGen provided an expert report alleging profit disgorgement damages of $135 million or, alternatively, $30.5 million in lost profit damages, but the report did not discuss how our actions allegedly caused NextGen's damages. In December 2019, we deposed NextGen's expert, gaining additional clarity on categories of alleged damages but not on the alleged theories of liability. A jury trial is set to begin on January 25, 2021. We believe NextGen's claims are without merit and will vigorously defend against them; however, there can be no assurances as to the outcome of the dispute. We have not concluded that a loss related to the claims raised by NextGen in its counterclaim is probable, nor have we accrued a liability related to these claims. Although a loss may be reasonably possible (as defined in ASC 450), we do not have sufficient information to determine the amount or range of reasonably possible loss in light of the inherent difficulty of predicting the outcome of litigation generally, the wide range of damages presented by NextGen's expert, and the continued lack of clarity on the causal connection between Cerner Corporation's and Cerner HS's actions and any alleged damages.
Loss Contingencies [Line Items]
Loss Contingency, Management's Assessment and Process	Cerner Health Services, Inc. ("Cerner HS"), a wholly owned subsidiary of Cerner Corporation, filed a lawsuit in the Chester County, Pennsylvania, Court of Common Pleas against NextGen Healthcare Information Systems, LLC ("NextGen") relating to a dispute arising out of a supplier relationship initially established between Siemens Health Services, Inc. and NextGen prior to the acquisition of the assets of Siemens Health Services, Inc. by Cerner HS in 2015. In September 2017, the court issued a preliminary injunction to prevent NextGen from refusing to honor certain contractual obligations to support Cerner HS's clients who use NextGen ambulatory EHR solutions. In September 2018, NextGen filed a counterclaim alleging breach of contract and tortious interference but did not specify its damages. In August 2019, NextGen provided an expert report alleging profit disgorgement damages of $135 million or, alternatively, $30.5 million in lost profit damages, but the report did not discuss how our actions allegedly caused NextGen's damages. In December 2019, we deposed NextGen's expert, gaining additional clarity on categories of alleged damages but not on the alleged theories of liability. A jury trial is set to begin on January 25, 2021. We believe NextGen's claims are without merit and will vigorously defend against them; however, there can be no assurances as to the outcome of the dispute. We have not concluded that a loss related to the claims raised by NextGen in its counterclaim is probable, nor have we accrued a liability related to these claims. Although a loss may be reasonably possible (as defined in ASC 450), we do not have sufficient information to determine the amount or range of reasonably possible loss in light of the inherent difficulty of predicting the outcome of litigation generally, the wide range of damages presented by NextGen's expert, and the continued lack of clarity on the causal connection between Cerner Corporation's and Cerner HS's actions and any alleged damages.
Lowe [Member]
Commitments and Contingencies Disclosure [Abstract]
Loss Contingency, Management's Assessment and Process	On April 4, 2018, Ruby L. Lowe, Guardian ad Litem for Michael A. Taylor, filed a lawsuit against Cerner Corporation in the Circuit Court for Clarke County, Virginia. On November 4, 2019, the Court substituted Cerner HS in place of Cerner Corporation as the defendant in the lawsuit. Plaintiff asserts claims of negligent product liability, negligence, and violations of the Virginia Consumer Protection Act. Plaintiff alleges that Mr. Taylor suffered injuries following his medical treatment at Virginia Hospital Center, a client of Cerner HS. Specifically, plaintiff asserts a software defect contributed to an order to monitor pulse oxygen not starting until a day after it was ordered, allegedly contributing to Taylor's injury. Plaintiff seeks an award of $50 million. A jury trial is set to begin on September 8, 2020. Although a loss may be reasonably possible (as defined in ASC 450), we do not have sufficient information to determine the amount or range of reasonably possible loss in light of the inherent difficulty of predicting the outcome of litigation generally, the wide range of damages presented by plaintiff, and the difficulty plaintiff will have proving that the solution was the proximate cause of plaintiff's harm.
Loss Contingencies [Line Items]
Loss Contingency, Management's Assessment and Process	On April 4, 2018, Ruby L. Lowe, Guardian ad Litem for Michael A. Taylor, filed a lawsuit against Cerner Corporation in the Circuit Court for Clarke County, Virginia. On November 4, 2019, the Court substituted Cerner HS in place of Cerner Corporation as the defendant in the lawsuit. Plaintiff asserts claims of negligent product liability, negligence, and violations of the Virginia Consumer Protection Act. Plaintiff alleges that Mr. Taylor suffered injuries following his medical treatment at Virginia Hospital Center, a client of Cerner HS. Specifically, plaintiff asserts a software defect contributed to an order to monitor pulse oxygen not starting until a day after it was ordered, allegedly contributing to Taylor's injury. Plaintiff seeks an award of $50 million. A jury trial is set to begin on September 8, 2020. Although a loss may be reasonably possible (as defined in ASC 450), we do not have sufficient information to determine the amount or range of reasonably possible loss in light of the inherent difficulty of predicting the outcome of litigation generally, the wide range of damages presented by plaintiff, and the difficulty plaintiff will have proving that the solution was the proximate cause of plaintiff's harm.