Preferred and Common Stockholder's Equity - Schedule of Stock Repurchases (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Stockholders Equity [Line Items]
Shares purchased and retired	1.1	1.2
Common stock and additional paid-in-capital reductions	$ 9.5	$ 10.2
Charges to retained earnings	$ 28.5	$ 35.4
Common Stock
Stockholders Equity [Line Items]
Shares purchased and retired	1.1	1.2