Summary of Significant Accounting Policies (Tables)

12 Months Ended

Jun. 30, 2018

Accounting Policies [Abstract]

Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block]

	Year Ended
	June 30, 2017
	As previously reported			Adjustments			As adjusted
Cash Flows from Investing Activities:
Net decrease / (increase) in restricted cash and cash equivalents held to satisfy client funds obligations	$	6,843.6		$	(6,843.6	)	$	—
Net cash flows provided by/ (used in) investing activities	5,730.4			(6,843.6		)	(1,113.2		)
Effect of exchange rate changes on cash, cash equivalents, restricted cash, and restricted cash equivalents	14.7			(22.7		)	(8.0		)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	(410.7		)	(6,866.3		)	(7,277.0		)
Cash, cash equivalents, restricted cash, and restricted cash equivalents, end of year	$	2,780.4		$	5,401.2		$	8,181.6
	Year Ended
	June 30, 2016
	As previously reported			Adjustments			As adjusted
Cash Flows from Investing Activities:
Net (increase) / decrease in restricted cash and cash equivalents held to satisfy client funds obligations	$	(8,218.2	)	$	8,218.2		$	—
Net cash flows (used in)/ provided by investing activities	(9,087.2		)	8,218.2			(869.0		)
Effect of exchange rate changes on cash, cash equivalents, restricted cash, and restricted cash equivalents	(11.0		)	2.3			(8.7		)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	1,551.8			8,220.5			9,772.3
Cash, cash equivalents, restricted cash, and restricted cash equivalents, end of year	$	3,191.1		$	12,267.5		$	15,458.6

Estimated Useful Lives

Data processing equipment	2 to 5 years
Buildings	20 to 40 years
Furniture and fixtures	4 to 7 years

Schedule of Earnings Per Share, Basic and Diluted

Years ended June 30,	Basic		Effect of Employee Stock Option Shares	Effect of Employee Restricted Stock Shares	Diluted
2018
Net earnings from continuing operations	$	1,620.8			$	1,620.8
Weighted average shares (in millions)	440.6		1.1	1.6	443.3
EPS from continuing operations	$	3.68			$	3.66
2017
Net earnings from continuing operations	$	1,733.4			$	1,733.4
Weighted average shares (in millions)	447.8		0.9	1.6	450.3
EPS from continuing operations	$	3.87			$	3.85
2016
Net earnings from continuing operations	$	1,493.4			$	1,493.4
Weighted average shares (in millions)	457.0		0.8	1.3	459.1
EPS from continuing operations	$	3.27			$	3.25

Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]

R. Recently Issued Accounting Pronouncements.

Recently Adopted Accounting Pronouncements

In March 2018, the Company adopted ASU 2018-02, "Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income." ASU 2018-02 allows companies to reclassify stranded tax effects resulting from the Tax Cuts and Jobs Act (the “Act”) from accumulated other comprehensive (loss)/income to retained earnings. The June 30, 2018 Consolidated Balance Sheets reflect the reclassification out of accumulated other comprehensive income and into retained earnings of $42.3 million. The Company's policy for releasing disproportionate income tax effects from AOCI utilizes the aggregate approach. Refer to Note 14 for additional detail regarding the components of the reclassification. The adoption of ASU 2018-02 did not have an impact on the Company's consolidated results of operations or cash flows.

Effective July 1, 2017, the Company adopted Accounting Standards Update ("ASU") 2016-18, "Statement of Cash Flows (Topic 230): Restricted Cash." ASU 2016-18 requires that the statement of cash flows explain the change during the period in the total of cash, cash equivalents, and restricted cash. The Company retrospectively adopted the new standard, and as a result included restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts presented on the Statements of Consolidated Cash Flows. Accordingly, the statement of cash flows has been revised to include restricted cash and restricted cash equivalents associated with funds held to satisfy client obligations, as a component of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result of this adoption, the Company adjusted the Statements of Consolidated Cash Flows from previously reported amounts as follows:

	Year Ended
	June 30, 2017
	As previously reported			Adjustments			As adjusted
Cash Flows from Investing Activities:
Net decrease / (increase) in restricted cash and cash equivalents held to satisfy client funds obligations	$	6,843.6		$	(6,843.6	)	$	—
Net cash flows provided by/ (used in) investing activities	5,730.4			(6,843.6		)	(1,113.2		)
Effect of exchange rate changes on cash, cash equivalents, restricted cash, and restricted cash equivalents	14.7			(22.7		)	(8.0		)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	(410.7		)	(6,866.3		)	(7,277.0		)
Cash, cash equivalents, restricted cash, and restricted cash equivalents, end of year	$	2,780.4		$	5,401.2		$	8,181.6
	Year Ended
	June 30, 2016
	As previously reported			Adjustments			As adjusted
Cash Flows from Investing Activities:
Net (increase) / decrease in restricted cash and cash equivalents held to satisfy client funds obligations	$	(8,218.2	)	$	8,218.2		$	—
Net cash flows (used in)/ provided by investing activities	(9,087.2		)	8,218.2			(869.0		)
Effect of exchange rate changes on cash, cash equivalents, restricted cash, and restricted cash equivalents	(11.0		)	2.3			(8.7		)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	1,551.8			8,220.5			9,772.3
Cash, cash equivalents, restricted cash, and restricted cash equivalents, end of year	$	3,191.1		$	12,267.5		$	15,458.6

Effective July 1, 2017, the Company adopted ASU 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairments.” ASU 2017-04 establishes a one-step process for testing goodwill for a decrease in value, requiring a goodwill impairment loss to be measured as the excess of the reporting unit’s carrying amount over its fair value. The guidance eliminates the second step of the current two-step process that requires the impairment to be measured as the difference between the implied value of a reporting unit’s goodwill with the goodwill’s carrying amount. The adoption of ASU 2017-04 did not have an impact on the Company’s consolidated results of operations, financial condition, or cash flows.

In July 2017, the Company adopted ASU 2017-01, "Business Combinations (Topic 805) - Clarifying the Definition of a Business." ASU 2017-01 clarifies the definition of a business in order to allow for the evaluation of whether transactions should be accounted for as acquisitions or disposals of assets or businesses. The adoption of ASU 2017-01 did not have a material impact on the Company's consolidated results of operations, financial condition, or cash flows.

Recently Issued Accounting Pronouncements

The following table summarizes recent ASU's issued by the Financial Accounting Standards Board ("FASB") that could have a material impact on the Company's consolidated results of operations, financial condition, or cash flows.

Standard	Description	Effective Date	Effect on Financial Statements or Other Significant Matters
ASU 2017-07 Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Post-retirement Benefit Cost	This standard requires reporting the service cost component in the same line item or items as other compensation costs arising during the period in the Statements of Consolidated Earnings. The other components of net periodic pension cost are required to be presented in the Statements of Consolidated Earnings separately from the service cost component. Such changes are to be applied retrospectively from the date of adoption. The ASU also allows only the service cost component to be eligible for capitalization, when applicable, prospectively from the date of adoption.	For fiscal years beginning after December 15, 2017. Early adoption is permitted.	The Company will adopt ASU 2017-07 beginning on July 1, 2018. This ASU will be applied retrospectively and will require the reclassification of the non-service cost components of the net periodic benefit cost from within the respective line items of our Statements of Consolidated Earnings to Other expense/(income), net. Also, the requirement set forth under this ASU only allows the service cost component of net periodic benefit cost to be capitalized. Refer to the table below for a summary of the reclassification required, as a result of this change, on the Company's consolidated results of operations for the years ended June 30, 2018 and 2017. The adoption of the new accounting rules only impacts the classification of expenses on the Statements of Consolidated Earnings with no impact to consolidated income, the Company’s statements of financial condition, or cash flows.
ASU 2016-02 Leases (Topic 842)	This update amends the existing accounting standards for lease accounting, and requires lessees to recognize most lease assets and lease liabilities on the balance sheet and to disclose key information about leasing arrangements. This ASU requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application.	For fiscal years beginning after December 15, 2018. Early adoption is permitted.	The Company will adopt ASU 2016-02 beginning on July 1, 2019. The Company has not yet determined the impact of this ASU on its consolidated results of operations, financial condition, or cash flows.

Standard	Description	Effective Date	Effect on Financial Statements or Other Significant Matters
ASU 2014-09 Revenue from Contracts with Customers (Topic 606)	This standard outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance, and has since issued additional amendments to ASU 2014-09. These new standards require an entity to recognize revenue depicting the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The new standards will also result in enhanced revenue related disclosures. Entities have the option to apply the new guidance under a retrospective approach to each prior reporting period presented or a modified retrospective approach with the cumulative effect of initially applying the new guidance recognized at the date of initial application within the Statements of Consolidated Financial Position.	For fiscal years beginning after December 15, 2017. Early adoption is permitted.	The Company has been assessing the impact of the new revenue recognition standard on its relationships with its clients. In fiscal 2017, the Company determined it will not early adopt the standard, and instead will adopt the new standard in its fiscal year beginning on July 1, 2018 and will apply the guidance under the full retrospective approach. The Company is complete with its comprehensive diagnostic of the measurement and recognition provisions of the new standard. The provisions of the new standard will primarily impact the manner in which the Company treats certain costs to fulfill contracts (i.e., implementation costs) and costs to acquire new contracts (i.e., selling costs). The provisions of the new standard will require the Company to capitalize and amortize additional implementation costs than those capitalized and amortized under current U.S. GAAP. Further, under current U.S. GAAP, the Company immediately expenses all selling expenses. The provisions of the new standard will require that the Company capitalize incremental selling expenses such as commissions and bonuses paid to the sales force for obtaining contracts with new clients and/or selling additional business to current clients. These capitalized expenses will be amortized over the expected client life and will result in a significant increase to our total assets of approximately $1.7 billion. While the Company grows, the impact of deferring and amortizing additional costs creates higher overall pre-tax income, net earnings, and earnings per share, when compared to current U.S. GAAP. The provisions of the new standard will not materially impact the timing or amount of revenue the Company recognizes. The Company is substantially complete in determining the impacts of all the disclosure requirements. The Company expects to disaggregate its revenue by its three strategic pillars (U.S. Integrated HCM Solutions, U.S. HRBPO Solutions and Global Solutions) with separate disaggregation for PEO pass-through revenues and Client Fund Interest revenues. Additionally, while the Company is in the process of assessing its accounting and forecasting processes to ensure its ability to record, report, forecast, and analyze results under the new standard, it is not expecting significant changes to its business processes or systems. As a result of this change, within the tables below, the Company preliminarily estimates the following impact to its consolidated results of operations for the years ended June 30, 2018 and 2017:

Estimated impact of adoption of ASU 2014-09 and ASU 2017-07 on the Statements of Consolidated Earnings:

	Year Ended
	June 30, 2018
	As reported		Adjustments ASC 606				Adjustments ASU 2017-07			As adjusted
Revenues, other than interest on funds held for clients and PEO revenues	$	8,985.2	$	(1.8	)		$	—		$	8,983.4
Interest on funds held for clients	$	466.5								$	466.5
PEO revenues	3,874.1		3.5				—			3,877.6
TOTAL REVENUES	13,325.8		1.7				—			13,327.5
Operating expenses	6,937.9		(74.0		)		37.2			6,901.1
Systems development and programming costs	630.2		—				7.6			637.8
Selling, general, and administrative expenses	2,971.5		(35.8		)		21.2			2,956.9
Total Expenses	10,916.8		(109.8		)		66.0			10,873.0
Other expense/(income), net	237.9						(66.0		)	171.9
EARNINGS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	2,171.1		111.5				—			2,282.6
Provision for income taxes	550.3		(165.6		)	*	—			384.7
NET EARNINGS FROM CONTINUING OPERATIONS	$	1,620.8	$	277.1			$	—		$	1,897.9

*Includes the impact of the remeasurement, as required by the Act, of deferred tax liabilities associated with the capitalized selling and implementation expenses created as a result of the adoption of ASC 606.

	Year Ended
	June 30, 2017
	As reported			Adjustments ASC 606			Adjustments ASU 2017-07			As adjusted
Revenues, other than interest on funds held for clients and PEO revenues	$	8,518.1		$	(8.0	)	$	—		$	8,510.1
Interest on funds held for clients	$	397.4								$	397.4
PEO revenues	3,464.3			0.3			—			3,464.6
TOTAL REVENUES	12,379.8			(7.7		)	—			12,372.1
Operating expenses	6,416.1			(63.5		)	33.8			6,386.4
Systems development and programming costs	627.5			—			6.6			634.1
Selling, general, and administrative expenses	2,783.2			(30.0		)	18.7			2,771.9
Total Expenses	10,133.0			(93.5		)	59.1			10,098.6
Other expense/(income), net	(284.3		)	—			(59.1		)	(343.4		)
EARNINGS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	2,531.1			85.8			—			2,616.9
Provision for income taxes	797.7			31.4			—			829.1
NET EARNINGS FROM CONTINUING OPERATIONS	$	1,733.4		$	54.4		$	—		$	1,787.8