Preferred and Common Stockholder's Equity - Schedule of Stock Repurchases (Detail) - USD ($) shares in Millions, $ in Millions	12 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Stockholders Equity [Line Items]
Shares purchased and retired	1.6	4.5
Common stock and additional paid-in-capital reductions	$ 14.6	$ 41.2
Charges to retained earnings	$ 17.0	$ 121.4
Common Stock [Member]
Stockholders Equity [Line Items]
Shares purchased and retired	1.6	4.5

Number of shares that have been repurchased and retired during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Name Accounting Standards Codification
-Topic 210
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Period Type:	duration