Subsequent Events (Notes)	12 Months Ended
Jun. 30, 2017
Subsequent Event [Line Items]
Subsequent Events [Text Block]	NOTE 19. SUBSEQUENT EVENTS On June 19, 2017, PAREXEL entered into an Agreement and Plan of Merger pursuant to which West Street Merger Sub, Inc., a Massachusetts corporation and a wholly-owned subsidiary of West Street Parent, LLC, a Delaware limited liability company (which we refer to as Parent) and affiliate of Pamplona Capital Management, LLP, will be merged with and into us, with PAREXEL surviving as a subsidiary of West Street Parent, LLC, which we refer to as the merger will acquire all of the outstanding shares of PAREXEL for $88.10 per share in cash in a transaction valued at approximately $5.5 billion, including PAREXEL’s net debt. Consummation of the merger is subject to various customary conditions, including adoption of the merger agreement by the Company’s stockholders and receipt of required regulatory approvals. The closing of the merger is expected to be completed late in the third quarter or early in the fourth quarter of calendar year 2017. Immediately prior to, and contingent upon, the closing of the merger, each outstanding Company stock option, restricted stock unit, restricted share and performance restricted stock unit (collectively, the “Company Equity Awards”) will vest in full (in the case of performance restricted stock units, at target level regardless of the actual achievement of the applicable performance metric). Such fully vested Company Equity Awards will be canceled and converted into the right to receive an amount in cash equal to $88.10 per share for each share of our common stock underlying such Company Equity Awards (net of any applicable exercise price and subject to any applicable withholding taxes). On August 15, 2017, the Company announced a special meeting of the shareholders of PAREXEL to be held on September 15, 2017. At the shareholder meeting, shareholders will be asked to consider and vote on a proposal to approve the Agreement and Plan of Merger, dated as of June 19, 2017, by and among PAREXEL, West Street Parent, LLC (“Parent”) and West Street Merger Sub, Inc. (“Merger Sub, providing for the acquisition of the Company by an affiliate of the private equity investment firm Pamplona. Subject to the terms and conditions of the Merger Agreement, the acquisition will occur by means of a merger of Merger Sub, a wholly-owned subsidiary of Parent, with and into the Company, with the Company surviving the merger as a wholly-owned subsidiary of Parent in accordance with the Massachusetts Business Corporation Act (the “MBCA”). We have incurred $10.0 million as of June 30, 2017, and will continue to incur, significant costs and expenses, including fees for professional services and other transaction costs, in connection with the merger.

NOTE 19. SUBSEQUENT EVENTS

On June 19, 2017, PAREXEL entered into an Agreement and Plan of Merger pursuant to which West Street Merger Sub, Inc., a Massachusetts corporation and a wholly-owned subsidiary of West Street Parent, LLC, a Delaware limited liability company (which we refer to as Parent) and affiliate of Pamplona Capital Management, LLP, will be merged with and into us, with PAREXEL surviving as a subsidiary of West Street Parent, LLC, which we refer to as the merger will acquire all of the outstanding shares of PAREXEL for $88.10 per share in cash in a transaction valued at approximately $5.5 billion, including PAREXEL’s net debt. Consummation of the merger is subject to various customary conditions, including adoption of the merger agreement by the Company’s stockholders and receipt of required regulatory approvals. The closing of the merger is expected to be completed late in the third quarter or early in the fourth quarter of calendar year 2017.

Immediately prior to, and contingent upon, the closing of the merger, each outstanding Company stock option, restricted stock unit, restricted share and performance restricted stock unit (collectively, the “Company Equity Awards”) will vest in full (in the case of performance restricted stock units, at target level regardless of the actual achievement of the applicable performance metric). Such fully vested Company Equity Awards will be canceled and converted into the right to receive an amount in cash equal to $88.10 per share for each share of our common stock underlying such Company Equity Awards (net of any applicable exercise price and subject to any applicable withholding taxes).

On August 15, 2017, the Company announced a special meeting of the shareholders of PAREXEL to be held on September 15, 2017. At the shareholder meeting, shareholders will be asked to consider and vote on a proposal to approve the Agreement and Plan of Merger, dated as of June 19, 2017, by and among PAREXEL, West Street Parent, LLC (“Parent”) and West Street Merger Sub, Inc. (“Merger Sub, providing for the acquisition of the Company by an affiliate of the private equity investment firm Pamplona. Subject to the terms and conditions of the Merger Agreement, the acquisition will occur by means of a merger of Merger Sub, a wholly-owned subsidiary of Parent, with and into the Company, with the Company surviving the merger as a wholly-owned subsidiary of Parent in accordance with the Massachusetts Business Corporation Act (the “MBCA”).

We have incurred $10.0 million as of June 30, 2017, and will continue to incur, significant costs and expenses, including fees for professional services and other transaction costs, in connection with the merger.