Summary of Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2013
Accounting Policies [Abstract]
Divestiture of Medical Management Professionals	*Divestiture of Medical Management Professionals* On July 26, 2013, CBIZ, through its subsidiary CBIZ Operations, Inc., an Ohio Corporation, entered into an agreement with Zotec Partners, LLC, an Indiana limited liability company, to sell all of the issued and outstanding capital stock of each of CBIZ Medical Management Professionals, Inc., an Ohio corporation, and CBIZ Medical Management, Inc., a North Carolina corporation, and substantially all of the stock of their subsidiary companies, collectively consisting of all of CBIZ’s Medical Management Professionals ongoing operations and business (“MMP”). The sale of MMP was completed on August 30, 2013 for a total purchase price of $201.6 million, subject to final working capital adjustments. After transaction costs and taxes, CBIZ estimates proceeds of approximately $145.4 million. See Note 13 for further discussion of discontinued operations and divestitures.
Stock Purchase Agreement with Westbury Ltd	*Stock Purchase Agreement with Westbury Ltd.* On August 30, 2013, concurrent with the sale of MMP, CBIZ completed an agreement with Westbury (Bermuda) Ltd., a Bermuda exempted company (“Westbury”), Westbury Trust, a Bermuda trust, and Michael G. DeGroote, the founder of CBIZ, to purchase from Westbury 3.85 million shares of the Company’s common stock, which was 50% of Westbury’s current holdings of the Company’s common stock, at a price of $6.65 per share.
Principles of Consolidation	*Principles of Consolidation* The accompanying consolidated financial statements reflect the operations of CBIZ, Inc. and all of its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The accompanying consolidated financial statements do not reflect the operations or accounts of variable interest entities as the impact is not material to the financial condition, results of operations or cash flows of CBIZ. See CBIZ’s Annual Report on Form 10-K for the year ended December 31, 2012 for further discussion.
Use of Estimates	*Use of Estimates* The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect: the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported amounts of revenue and expenses. Management’s estimates and assumptions include, but are not limited to, estimates of collectability of accounts receivable and unbilled revenue, the realizability of goodwill and other intangible assets, the fair value of certain assets, the valuation of stock options in determining compensation expense, estimates of accrued liabilities (such as incentive compensation, self-funded health insurance accruals, legal reserves, income tax uncertainties, contingent purchase price obligations, and consolidation and integration reserves), the provision for income taxes, the realizability of deferred tax assets, and other factors. Management’s estimates and assumptions are derived from and are continually evaluated based upon available information, judgment and experience. Actual results could differ from those estimates.
Revenue Recognition and Valuation of Unbilled Revenues	*Revenue Recognition and Valuation of Unbilled Revenues* Revenue is recognized only when all of the following are present: persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the fee to the client is fixed or determinable, and collectability is reasonably assured. CBIZ offers a vast array of products and business services to its clients. Those services are delivered through three practice groups. A description of revenue recognition policies is included in the Annual Report on Form 10-K for the year ended December 31, 2012.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2013

Divestiture of Medical Management Professionals

Divestiture of Medical Management Professionals

On July 26, 2013, CBIZ, through its subsidiary CBIZ Operations, Inc., an Ohio Corporation, entered into an agreement with Zotec Partners, LLC, an Indiana limited liability company, to sell all of the issued and outstanding capital stock of each of CBIZ Medical Management Professionals, Inc., an Ohio corporation, and CBIZ Medical Management, Inc., a North Carolina corporation, and substantially all of the stock of their subsidiary companies, collectively consisting of all of CBIZ’s Medical Management Professionals ongoing operations and business (“MMP”). The sale of MMP was completed on August 30, 2013 for a total purchase price of $201.6 million, subject to final working capital adjustments. After transaction costs and taxes, CBIZ estimates proceeds of approximately $145.4 million. See Note 13 for further discussion of discontinued operations and divestitures.

Stock Purchase Agreement with Westbury Ltd

Stock Purchase Agreement with Westbury Ltd.

On August 30, 2013, concurrent with the sale of MMP, CBIZ completed an agreement with Westbury (Bermuda) Ltd., a Bermuda exempted company (“Westbury”), Westbury Trust, a Bermuda trust, and Michael G. DeGroote, the founder of CBIZ, to purchase from Westbury 3.85 million shares of the Company’s common stock, which was 50% of Westbury’s current holdings of the Company’s common stock, at a price of $6.65 per share.

Principles of Consolidation

Principles of Consolidation

The accompanying consolidated financial statements reflect the operations of CBIZ, Inc. and all of its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The accompanying consolidated financial statements do not reflect the operations or accounts of variable interest entities as the impact is not material to the financial condition, results of operations or cash flows of CBIZ. See CBIZ’s Annual Report on Form 10-K for the year ended December 31, 2012 for further discussion.

Use of Estimates

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect: the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported amounts of revenue and expenses. Management’s estimates and assumptions include, but are not limited to, estimates of collectability of accounts receivable and unbilled revenue, the realizability of goodwill and other intangible assets, the fair value of certain assets, the valuation of stock options in determining compensation expense, estimates of accrued liabilities (such as incentive compensation, self-funded health insurance accruals, legal reserves, income tax uncertainties, contingent purchase price obligations, and consolidation and integration reserves), the provision for income taxes, the realizability of deferred tax assets, and other factors. Management’s estimates and assumptions are derived from and are continually evaluated based upon available information, judgment and experience. Actual results could differ from those estimates.

Revenue Recognition and Valuation of Unbilled Revenues

Revenue Recognition and Valuation of Unbilled Revenues

Revenue is recognized only when all of the following are present: persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the fee to the client is fixed or determinable, and collectability is reasonably assured.

CBIZ offers a vast array of products and business services to its clients. Those services are delivered through three practice groups. A description of revenue recognition policies is included in the Annual Report on Form 10-K for the year ended December 31, 2012.

- Definition

Disclosure of accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example, common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting. The accounting policy may also address the accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.

+ References

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+ Details

- Definition

Disclosure of accounting policy for any discontinued operations. The results of operations of a component of an entity that either has been disposed of or is classified as held for sale is reported in discontinued operations if both: (a) the operations and cash flows of the component have been (or will be) eliminated from the ongoing operations of the entity as a result of the disposal transaction and (b) the entity will not have any significant continuing involvement in the operations of the component after the disposal transaction. If the entity elects to allocate interest expense to a discontinued operation, it may disclose its accounting policy for this election and describe its method of allocation.

+ References+ Details

- Definition

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.

+ References+ Details