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Fair Value Measurements - Schedule of Fair Value of Financial Assets (Detail) - USD ($) $ in Millions | Jun. 30, 2017 | Jun. 30, 2016
--- | --- | ---
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets and liability |  | $ (24.8) | $ 162.4
Money Market Funds [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets | [1] | 7.4 | 2.4
Corporate Bonds and Notes [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets |  | 50.4 | 51.0
Municipal Bonds [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets |  | 36.9 | 85.6
Federal Agency Issues [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets |  | 13.8 | 25.5
US Government Securities [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets |  | 7.2 | 8.3
Contingent Consideration [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial liability |  | (140.5) | (10.4)
Level 1 [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets and liability |  | 7.4 | 2.4
Level 1 [Member] | Money Market Funds [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets | [1] | 7.4 | 2.4
Level 2 [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets and liability |  | 108.3 | 170.4
Level 2 [Member] | Corporate Bonds and Notes [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets |  | 50.4 | 51.0
Level 2 [Member] | Municipal Bonds [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets |  | 36.9 | 85.6
Level 2 [Member] | Federal Agency Issues [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets |  | 13.8 | 25.5
Level 2 [Member] | US Government Securities [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets |  | 7.2 | 8.3
Level 3 [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial assets and liability |  | (140.5) | (10.4)
Level 3 [Member] | Contingent Consideration [Member] |  |  |
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] |  |  |
Total fair value of financial liability |  | $ (140.5) | $ (10.4)
[1] | Money market funds are primarily comprised of exchange traded funds and accrued interest

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